Ethiopian airliner down in Africa

[Organfreak]

There are two lines of thinking here: it was a poor aircraft and they were poor pilots. Let me explore both, using the "why" system:
1. The aircraft had hidden killer behaviour because it was a financial requirement to have a common TR because the regulator allowed this because the regulator is weak.
2. The crew performed poorly because they were inadequately trained because it was a common TR which was allowed because the regulator is weak.

If we boil this down, it doesn't really matter whether you subscribe to pilot error or Boeing error or both.

Both. Congrats. You have won the Internet for today.

[HundredPercentPlease]

Both. Congrats. You have won the Internet for today.

Lol!

I would suggest then that every party bar one wants better regulators:

Manufacturers, so the pilots are well trained and don't destroy their aircraft.
Pilots, so the manufacturers make safe aircraft.
Passengers, for both the above reasons.

The only party who wants poor regulators is the airlines - and that's for greed reasons.

[Organfreak]

The only party who wants poor regulators is the airlines - and that's for greed reasons.

Quite. Welcome to 2019. So I would submit that, given the environment in which we find ourselves, it's no wonder that 737 Driver insists that we know how to fly the damn plane. Seems pragmatic and very healthy. This debate doesn't need to be so polarized.

[MurphyWasRight]

Originally Posted by 737 Driver https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-post10458143.html#post10458143)
retract the flaps) when it was not appropriate (particularly retracting the flaps given what was known about MCAS).
How did he know he was going to have an MCAS event? He was dealing with a stall warner that shouldn't have been warning.


Auto pilot was also a 'known' protection against MCAS as mentioned in one of the safety reports a page back or so.
Had the auto pilot stayed engaged another couple of minutes we might not be having this discussion.

Btw: I am not faulting the auto pilot (probably the only thing that is mostly innocent) or agree with decision to engage it given stick shaker etc.

[HundredPercentPlease]

Quite. Welcome to 2019. So I would submit that, given the environment in which we find ourselves, it's no wonder that 737 Driver insists that we know how to fly the damn plane. Seems pragmatic and very healthy. This debate doesn't need to be so polarized.

I only disagree with 737 Driver over his assertion that flying the aircraft in those circumstance was always achievable. I maintain that for many crews it would have been unachievable, owing to the combined human factor issues that saturate the environment, inhibiting the execution of normal flying skills. In my experience of major failures in real life, getting over the hill is harder than you think. Much harder. And very low hour FOs are very, very useful. Controversial, I know (especially to US pilots), but that's what I discovered for real.

[Alchad]

No, of course I don't.

Who ramped this up to "LEGAL", this isn't a court of law. Or are you changing the rules midstream?

No kangaroo court - back to hysterical overstatement again! The evidence for pilot's actions? The preliminary reports and the data traces are all we have to go on but they're enough to tell a great deal. Or do you hold them discredited due to some hitherto unsuggested collusion or corruption?

I'm surprised you even need to ask that question...


I wasn't changing the rules just seeking to separate which things I should give more weight. I added "LEGAL" to mean officially sanctioned findings that have considered all available evidence rather than subjective personal, opinions which, however qualified the authors may be as pilots or whatever are merely that - subjective. The preliminary reports and data are just that, preliminary. My (your view) "hysterical overstatement " comment about a kangaroo court was simply trying to draw the distinction between judgments made with full evidence and those which are personal opinions.

My original question to you was trying to point out the contradiction between your "Despite the amount of unequivocal evidence of misdeeds by the pilots" and your wish for evidence to be present evidence and discuss it rationally. My reading of the posts on this thread by qualified pilot does lead me to conclude that everyone is of that opinion and I merely suggesting that before making such a statement you should provide evidence of such.

Finally, as for your "hysterical overstatement" remark, you might like to go back and re-read your post where phrase such statements abound "hysteria ramps up and wild totally unsubstantiated accusations of bodgery etc etc", "shrill and baseless …. nothing short of scurrilous etc etc". You might also like to check out other posts on this thread (eg FAA getting comments on their whistleblower phoneline) which suggest that these unsubstantiated accusations are less than unsubstantiated.

Sorry that I had to take up your time explaining this again.

[Bergerie1]

wonkazoo, I have sent you a PM

[GordonR_Cape]

Auto pilot was also a 'known' protection against MCAS as mentioned in one of the safety reports a page back or so.
Had the auto pilot stayed engaged another couple of minutes we might not be having this discussion.

Just to clarify something which was discussed previously: Enabling the autopilot would certainly inhibit MCAS. However this is only true if there were no other factors in play. In the accident scenarios the problems cascaded, and AOA disagree triggered unreliable airspeed, which limited the possibility that the autopilot could be used to inhibit MCAS.

Analysing all of this in a short period of time, would have required exceptional knowledge, and in the absence of an AOA value or AOA disagree display, an understanding of the links between the sensors and the flight systems may have been beyond the scope of the crew.

[MurphyWasRight]

Just to clarify something which was discussed previously: Enabling the autopilot would certainly inhibit MCAS. However this is only true if there were no other factors in play. In the accident scenarios the problems cascaded, and AOA disagree triggered unreliable airspeed, which limited the possibility that the autopilot could be used to inhibit MCAS.

Analysing all of this in a short period of time, would have required exceptional knowledge, and in the absence of an AOA value or AOA disagree display, an understanding of the links between the sensors and the flight systems may have been beyond the scope of the crew.

My earlier point was that the autopilot was engaged for about 35 seconds, this could have tricked the pilot into thinking things were (more or less) ok spurious warnings only, this led to flap retraction.This is supported by the almost normal seeming events in cockpit at this time, selecting altitude etc

Flap retraction led to 2 things in short order:
1: Autopilot dropped off.
2:Mcas added it's first ND input.

So the pilot was dealing with 2 things at once.

[HundredPercentPlease]

Flap retraction led to 2 things in short order:
1: Autopilot dropped off.
2:Mcas added it's first ND input.

So the pilot was dealing with 2 things at once.

1: Autopilot dropped off.
2: Mcas added it's first ND input.
3. Stick shaker still going off and fault not resolved.
4. Unreliable airspeed.
5. ATC blah blah

Overload.

[PaxBritannica]

Am I right in thinking that - even with the 'fix' - there will be no clear indication to the pilot that MCAS has kicked in? If the difference between AOA sensors is less than 5.5 degrees, does this mean that even the little mustard 'AOA-disagree' alert won't show, but MCAS will fire if other conditions are met?

I guess this means that pilots will have to infer that MCAS is live from the uncommanded AND, having quickly checked whether the other conditions apply (flaps, autopilot)?

I can't see that this does much to advance the pilot's ability to diagnose the problem. Why can't some space be found for a flashing red 'MCAS active' alert to show exactly what's happening?

[HundredPercentPlease]

No space needed if a voice says "MCAS MCAS" as it's trimming.

If you're not in the high AoA regime (ie it's faulty) then that would be a great time to flick the switches.

No hardware mods required.

[Rananim]

737 Driver isnt going away...and thats lucky for us.What he says is undeniably true.
These accidents are not just about MCAS.
I think we need to focus on UAS.Boeing article below discusses it best.The uncertainty
when faced with conflicting or spurious data can be unsettling.The alarms can make it
a real test of focus over distraction.If trained in UAS,the startle factor is surmountable,
recovery is always assured.If not,things can go south pretty quick.
Training,experience,airmanship is everything.Nothing else matters.Nothing.
Erroneous Flight Instrument Information - Text Only (http://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.html)

[737 Driver]

737 driver, looking at the TO greenband, on the 738, (and all other NG that I can remember)it is 1.5 to 6.5, while on the MAX it is 3 to 8...this is a significant difference. Thoughts?

Not sure where you are getting those numbers as they don't match what's in my FCOM. (Actually, no actual numbers are provided, but I can read the pictures :O ). My thoughts are this: the manufacturer determines what the allowable range is and my job is to stay with that range. That being said, after a certain amount of time with any aircraft, one should have a decent idea of what a "normal" trim setting should be. But once again, I don't know any pilot who flies around and sets the trim by looking at the index. You set it by feel. The index isn't even the most useful visual tool to clue you into a runaway trim. That honor goes to the trim wheel. It takes about 15 rotations to make one degree of movement, and it has a bright white stripe that flashes at you as the wheel is spinning. Hard to miss if you are looking at it.

[BluSdUp]

I think the point is the Max has a nose heavy empty weight and that the take off trim band ( Green) has been moved aft to compensate!
The question is did Boeing have to move/ expand the rest of the envelope to avoid restrictions on the loading of the aircraft making a not so fantastic economic choice?

[Organfreak]

Am I right in thinking that - even with the 'fix' - there will be no clear indication to the pilot that MCAS has kicked in? [SNIP]

I guess this means that pilots will have to infer that MCAS is live from the uncommanded AND, having quickly checked whether the other conditions apply (flaps, autopilot)?

I can't see that this does much to advance the pilot's ability to diagnose the problem. Why can't some space be found for a flashing red 'MCAS active' alert to show exactly what's happening?

No, Boeing has stated (I read it here somewhere) that there will be a warning light/message when MCAS is engaged.

[edmundronald]

According to the WSJ, and taken up by CNBC, it now seems the AoA disagree functionality in the Max airframes belonging to SWA was DISABLED, and some FAA officials contemplated grounding the plane.


Southwest Airline’s statement:

Upon delivery (prior to the Lion Air event), the AOA Disagree lights were depicted to us by Boeing as operable on all MAX aircraft, regardless of the selection of optional AOA Indicators on the Primary Flight Display (PFD). The manual documentation presented by Boeing at Southwest’s MAX entry into service indicated the AOA Disagree Light functioned on the aircraft, similar to the Lights on our NG series. After the Lion Air event, Boeing notified us that the AOA Disagree Lights were inoperable without the optional AOA Indicators on the MAX aircraft. At that time, Southwest installed the AOA Indicators on the PFD, resulting in the activation of the AOA Disagree lights - both items now serve as an additional crosscheck on all MAX aircraft.

Federal Aviation Administration (https://www.cnbc.com/faa/) safety inspectors and supervisors were also unaware of the change, according to government and industry officials that spoke to The Wall Street Journal (https://www.wsj.com/articles/boeings-enduring-puzzle-why-certain-safety-features-on-737-max-jets-were-turned-off-11556456400?mod=hp_lead_pos1).



https://www.cnbc.com/2019/04/28/boeing-didnt-tell-southwest-that-safety-feature-on-737-max-was-turned-off-wsj.html


Edmund

[737 Driver]

The report does state that the FO called trim runaway so he was not totally inert.
There is a saying in medicine that rare conditions are most likely to be diagnosed by bright interns or very experienced doctors. The intern does not have the experience to reject improble diagnoses while the very experienced are more likely to pick up on the "something does not fit" observations. From your description one would have to say the Captain was in the moderately (at best) experienced category.

I would have given a gold star to the First Officer if he had called for the trim cutout switches the first time MCAS took its 9-second, 37-spin journey toward oblivion. But yes, he did eventually see what the Captain did not, and that should be acknowledged. However, beside that one expression of independent thought and assertiveness, I pretty much see a First Officer doing what he is asked to do.

To be fair, it is entirely possible that more was being in said in the cockpit than what has been released in the transcript, though I would think any relevant comments would have been included. What strikes me most about the CVR transcript is not so much what is being said, but what is not.

There is obviously something wrong with the aircraft. The Captain is struggling to maintain control. I see little if any cross-talk about airspeeds, altitudes, power settings, etc. I see no discussion regarding non-normals. Other than the stab trim cutout call, I do not see the First Officer prompting the Captain in any meaningful way.

I do see a lot of (mostly unnecessary) communicating with and about ATC. Ever hear the phrase, "Aviate, navigate, communicate"? If you don't have the first item under control, then you don't have much business moving onto the third.

Part of every briefing I give at the beginning of a trip with a new FO (or one I have not flown with recently) is this statement: "Each and every leg of this trip I am absolutely guaranteed to screw up at least one thing. Please note that I say at least, and not only, one thing. Your job is to catch my mistakes, and my job is to catch yours."

I fly, I am human, humans err, therefore I err when I fly. QED. This is the foundational message of the crew concept. A good First Officer is more than a co-worker who flies the aircraft according to the airline's scripts and follows the direction of the Captain. A good First Officer not only knows their aircraft and procedures, but he/she is also assertive enough to speak up when the Captain is going off into the weeds. At every point that the Captain was doing something that was either inadvisable or ineffective, a good First Officer should have spoken up. In extreme cases of Captain befuddlement, a First Officer should say loudly and firmly "My Aircraft!" and do what needs to be done to save the ship. None of these things happened.

I haven't been too hard on the FO, because I don't really expect much from a 360-hour, three-month pilot. It is my personal opinion that this gentleman was simply put in a situation beyond his capacity to function effectively. Some people have suggested that I shouldn't be so biased against a low-time pilot. Well, if that's truly the case, then they probably won't like what I have to say about the FO's performance either.

[737 Driver]

I think the point is the Max has a nose heavy empty weight and that the take off trim band ( Green) has been moved aft to compensate! The question is did Boeing have to move/ expand the rest of the envelope to avoid restrictions on the loading of the aircraft making a not so fantastic economic choice?

I have no data to suggest that changes any changes to the c.g. envelope have any meaningful impact to the operation of the MAX vs the NG. During normal airline operations, it is highly unusual to see this aircraft loaded anywhere near a limit. That generally comes up only on ferry/reposition flights with certain fuel loads or situations where a cargo compartment is placarded.

[MurphyWasRight]

Just noticed this on AV herald, if true it is shocking and may explain some of the crews confusion/actions. My bolding, strongly suggest reading the whole article at:
Crash: Ethiopian B38M near Bishoftu on Mar 10th 2019, impacted terrain after departure (http://avherald.com/h?article=4c534c4a/0045&opt=0)

Coverage released on Apr 16th:

On Apr 11th 2019 The Aviation Herald received a full copy of the Flight Operations Manual (FOM), Revision 18B released on Nov 30th 2018, which is currently being used by Ethiopian Airlines (verified in April 2019 to be current). Although Boeing had issued an operator's bulletin on Nov 6th 2018, which was put into Emergency Airworthiness Directive 2018-23-51 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/eff7ed6468ccd134862575e000837739/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf) dated Nov 7th 2018 requiring the stab trim runaway procedure to be incorporated into the FOM ahead of the sign off of this version of the FOM (the entire document is on file but not available for publishing), there is no trace of such an addition in the entire 699 pages of the FOM.

...
...
It turned out, that only very cursory knowledge about the stab trim runaway procedure exists amongst the flight crew of Ethiopian Airlines even 5 months after the EAD was distributed.
...
...


I may have missed this if it was posted earlier, it is hard to keep up given the volume of posts.

[737 Driver]

How did he know he was going to have an MCAS event? He was dealing with a stall warner that shouldn't have been warning.

Not sure what you mean by a warning that shouldn't have been a warning. As to the question why the Captain should have at least considered the possibility of a MCAS event, then I should ask in return why would the Captain be so unaware of the circumstances surrounding Lion Air 610? Lot's of information was in circulation regarding MCAS, it's operating parameters, and the things one would expect to see in case of a AOA-malfunction after this accident. Some here have even suggested that the fear of this being another Lion Air type event may have been one of the things that caused the Captain's brain to go up and locked. I'll grant the possibility that Ethiopian Airlines may have done a piss poor job of passing the information along, and perhaps the Captain did not have the inclination or resources to research it himself. However, that still leaves us with the fact that crew was faced first with an AOA failure that was handled poorly which then set them up for a runaway trim event that was handled worse.


I would avoid making assumptions about the skills of the crews. In Europe it's easy to do too - we hear incompetent sounding fat cigar chewing fools who don't know that you can have a flight level of 90, but we try to remember that judging ability by nationality or assumed education is very, very wrong.

I am not judging the crew by nationality or education. I am judging them by the smoking hole they left at the abrupt termination of their flight.

[PerPurumTonantes]

exactly how long should a qualified 737 type-certified Captain who is hand-flying the aircraft let the trim run in one direction before he/she does something about it?
​​​​​​​

In quiet cockpit, vmc, no distractions, no turbulence, hands on controls: 3 seconds. 1: a/c is just "doing its thing". 2: thats weird. 3: wtf? Hit elec trim.

But. With stick shaker distraction: add time. With any other alarm, add more time. Add IMC, double it. If you're concentrating on another task: Add time. With noise that masks clacks: more time. Add "I have control" there's another half second. Add fatigue: more time.

MCAS is a slow-motion catastrophic control surface failure, taking 12 seconds. (For those who haven't followed all 228 pages of this thread, see this post (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-220.html#post10456545) detailing why MCAS is so insidious and lethal to a pilot.) You're treating it like an engine fail on takeoff. It has more in common with wonkazoo's snapped rudder cable (https://www.pprune.org/showthread.php?p=10456057). An engine fail on takeoff you'd pretty much expect to see at some point in your career. Before Lion Air and ET, no-one would be expecting to see trim runaway. This surprise factor again adds time.

They ran out of time.

Every time you say 'just fly the plane' or 'basic airmanship' or 'get another career' you're completely ignoring human factors. This is as dangerous as not knowing how to fly the aircraft. And this is why you're getting such a deservedly robust response from others on here.

[TryingToLearn]

I did not read the discussion for a weak and I find it partly very useless.
As an (automotive) safety engineer, I categorize the 'controllability' of an event in simple (>99%), normal (>90%) or difficult (<90%) according to ISO26262.
And yes, difficult and uncontrollable are the same.
So as long as less than 90% of the pilots here are saying 'piece of cake', it's the same as uncontrollable.
The reason is very easy: If you design a system, you can estimate an order of magnitude of the error probability. Sensor redundancy doubles the number fields on your lottery ticket, so would you bother about the exact probability, third digit? Probably not if you're going from one in a million to one in a trillion (lost flights / winning tickets...).
What's better? Rely on the estimate that 70% of professional pilots can handle the event with training instead of 40% or just make it one in a million years instead of 2 times in 4 months by a simple plain stupid sensor compare of existing sensors?

Together with other estimates (exposure, severity), where MCAS has both won the jackpot (highly probable situation with fatal outcome), this looks like a highly critical system to me.

As an engineer, this tells you that you really need redundancy. There is always a remaining probability (like lot's of goose at low attitude as common cause for a dive in the Hudson...) where the pilot may have a chance of not being part of the 'remaining accepted risk of flying' by our society. But how often did it happen? Based on how many planes in the air? Would anyone blame the captain if this would have gone wrong?
Recently I read the report and told another safety engineer that the FBW system prevented a stall while the pilot pulled the stick and would have caused it. The first question I got was: Did he count on this function? Like with ESP: you do not longer consider blocking tires, just press hard... The automation assists you even in critical situations, that's state of the art (instead of 37 turns on a handwheel).

The obvious underestimation of this MCAS function is one thing, but no engineer would DEACTIVATE an existing diagnostic function while at the same time ADDING a safety critical system to the (no longer) diagnosed input.
Especially with the explanation that this one true warning may cause side effects while the pilot gets ****loads of false ones (stickshaker...). But media reports indicate that this is the case.

This would scream at you at so many stages of the design process that it would be almost impossible to overlook. Except there is something wrong with your process..

In addition, if this turns out to be a defective cabling as whistleblowers describe, it would make things even far worse:
-> Cabling diagnostics are the first thing an engineer does on EVERY cable he can find. It's easy to implement and cuts the error probability a lot.
-> Range check is the second one and a no-brainer... (which pilot did ever encounter a real/plausible AoA of 75° from below? Free-fall at 0 speed, flying in reverse gear or over an active volcano?)
-> If this was due to a foreign object close to the cabling, this opens up another big question mark: Production quality?

So if this turns out to be a management decision (or management decisions involved), good night Boeing... The 'training penalty' definitely counts as a motivation to do so.
Not because of MCAS but because it would put all decisions regarding safety of the last years into question since they could also be infected by financial aspects (including the FAA).

In my opinion everything points in this direction, since this thing is too big to be overseen within the safety engineering process.

But please, point the discussion in the direction of duct tape in the cockpit in case the pilot has to tape the wings back in place like every real pilot would do...
You couldn't do Boeing a bigger favour than this. Fighting the value of the third digit while there are several digits missing and maybe enough holes in the cheese for other surprises.

PS: Yesterday I had a turnament on ballroom dancing, first one after a long break. I trained for years and guess what: I learned that I need to dance the choreography I trained for months once directly before the turnament because with all the adrenaline in my blood I simply could not remember it / access my long term memory. It's like a tunnel, lost, gone for a moment... Ballroom competition dancing is considered one of the sports with the highest stress hormon levels (competitive sports + thinking + uncontrollable factors like your partner) and I finally realized what that means and does to you...
Having his life immediately threatened is probably far better than this, and the pilots had the full load ('sportive-elevator-pulling' + thinking + a mad MCAS). Nothing prepares you for this, no simulator, simply nothing... It may be comparable to doing a math test after your first bungee jump with fear of heights after a fast run... Simply do the math... sure...

[737 Driver]

​​​​​​

In quiet cockpit, vmc, no distractions, no turbulence, hands on controls: 3 seconds. 1: a/c is just "doing its thing". 2: thats weird. 3: wtf? Hit elec trim.

But. With stick shaker distraction: add time. With any other alarm, add more time. Add IMC, double it. If you're concentrating on another task: Add time. With noise that masks clacks: more time. Add "I have control" there's another half second. Add fatigue: more time.

MCAS is a slow-motion catastrophic control surface failure, taking 12 seconds. (For those who haven't followed all 228 pages of this thread, see this post (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-220.html#post10456545) detailing why MCAS is so insidious and lethal to a pilot.) You're treating it like an engine fail on takeoff. It has more in common with wonkazoo's snapped rudder cable (https://www.pprune.org/showthread.php?p=10456057). An engine fail on takeoff you'd pretty much expect to see at some point in your career. Before Lion Air and ET, no-one would be expecting to see trim runaway. This surprise factor again adds time.

They ran out of time.

Every time you say 'just fly the plane' or 'basic airmanship' or 'get another career' you're completely ignoring human factors. This is as dangerous as not knowing how to fly the aircraft. And this is why you're getting such a deservedly robust response from others on here.

Not ignoring the human element at all. Yes, the Captain was sufficiently distracted that he failed to take the most basic steps to fly his aircraft. There are all sorts of reasons why this can happen, but my point is that it should not have happened.

A significant part of the training of a professional pilot is how to handle things when things are going wrong. There is not a one of us who hasn't been in a sim when lights were flashing, alarms were blaring, systems were malfunctioning and the plane was trying to do something that it wasn't supposed to do. Is there some specified level of distraction at which we are excused from doing our job? If there is, I haven't heard of it.

And what is that job? At a minimum, when all is going to hell and you are really not sure what else to do - FLY THE AIRCRAFT. Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. Do that until your head clears and you can sort out what else needs to be done. This action should be as reflexive as executing your takeoff reject procedures - if you have to think about it, you're too late.

Being able to respond correctly under pressure and distraction is one of those things professional pilots are supposed to train for and expected to do. There is no "pause" button we can hit to stop the motion. We need to have the ability to shake off the distractions and FLY THE AIRCRAFT, first, last, and always. Yes, there is some level of turmoil that will overcome the best of us, but the events surrounding these accidents come no where near that threshold.

[MurphyWasRight]

FLY THE AIRCRAFT. Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. .
FLY THE AIRCRAFT. :: I suspect no arguments from anyone here, one wonders about the initial normalcy of ATC comm etc.

Turn off the magic, :: The only (documented) way to do this was using the trim cutouts, which they did do.

set the pitch, :: the were pulling the whole time with little change in displayed pitch, some oscillations after trim cutout.

set the power, :: Crew left it at takeoff, speed reached and settled at near/just over VMO after trim cutout.

monitor the performance, :: don'n know enogh to comment, other than noticing speed, but they may have not have had confidence in instruments.

trim the aircraft, :: One has to believe they were trying once cutout, may have wasted some time if only right switch was selected in mistaken belief that manual electric would still be available as on NG. Unfortunalty no detail in prelim report.

move to a safe altitude. . :: require pitch control, although they were gradually climbing until the end.

[wonkazoo]

Not ignoring the human element at all. Yes, the Captain was sufficiently distracted that he failed to take the most basic steps to fly his aircraft. There are all sorts of reasons why this can happen, but my point is that it should not have happened.

A significant part of the training of a professional pilot is how to handle things when things are going wrong. There is not a one of us who hasn't been in a sim when lights were flashing, alarms were blaring, systems were malfunctioning and the plane was trying to do something that it wasn't supposed to do. Is there some specified level of distraction at which we are excused from doing our job? If there is, I haven't heard of it.

And what is that job? At a minimum, when all is going to hell and you are really not sure what else to do - FLY THE AIRCRAFT. Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. Do that until your head clears and you can sort out what else needs to be done. This action should be as reflexive as executing your takeoff reject procedures - if you have to think about it, you're too late.

Being able to respond correctly under pressure and distraction is one of those things professional pilots are supposed to train for and expected to do. There is no "pause" button we can hit to stop the motion. We need to have the ability to shake off the distractions and FLY THE AIRCRAFT, first, last, and always. Yes, there is some level of turmoil that will overcome the best of us, but the events surrounding these accidents come no where near that threshold.

I'm sorry 737 Driver for my failure to express to you the reality of what happened as opposed to your jaundiced view of what should have happened. I'm going to take one more stab here for the benefit of others reading this thread, alas I do realize I am likely tilting at windmills.

"There is not a one of us who hasn't been in a sim when lights were flashing, alarms were blaring, systems were malfunctioning and the plane was trying to do something that it wasn't supposed to do. Is there some specified level of distraction at which we are excused from doing our job? If there is, I haven't heard of it."

While you were sitting there in the sim your body's adrenal system is sitting quietly, secure in the knowledge that the furthest you will fall is the ten feet down the entry stairs when you exit your session. I don't care how many alarms you are facing in a simulation- it is, by definition, a simulation. On the other hand, coming face to face in an instant with the knowledge and reality that your life is about to end and it may or may not be in your control to alter that course will cause your adrenal system to kick into high gear, almost certainly to an extent you have never experienced before. Having experienced this myself and in a literal life or death moment I can attest to the fact that the reaction of your body is going to cause things to happen that you basically can't even imagine. So first things first: There is no way to test for how an individual will react in such a circumstance, just like there is no way to simulate such an occurrence. Stop fantasizing about the day you will heroically react perfectly and save the day. You won't, and if you do save the day it will be in spite of your own body's reactions, not because of them.

"Being able to respond correctly under pressure and distraction is one of those things professional pilots are supposed to train for and expected to do."

Sorry, but that is so much macho BS, and it undercuts and underlies everything you have written. Once again: Could the pilots have done better?? Yes. But placing yourself in their position and declaring loudly and repeatedly that you would have done great had you been there and all they had to do was fly the airplane is simply gross ignorance writ large. Each crew had a cascading series of complex failures, at the end of which a little hidden genie would politely but insistently spool the trim forward until the airplane was in an unrecoverable state. Lest we forget- the ET crew did cuotout the trim, they just didn't do it quickly enough to prevent yet another hidden factor from coming into play.

Finally: "We need to have the ability to shake off the distractions and FLY THE AIRCRAFT, first, last, and always."

From an obviously intelligent guy/gal that is the most ignorant piece of horse$hit I've seen offered here. You (Yes, I mean 737 Driver in this instance) are no more able to "shake off" the effects of your adrenal system than I am able to become an African American female. It is insulting and denigrates our noble profession to continue to offer the "hero pilot" trope as the answer to everything human that goes sideways in a cockpit. It's because of ignorance like this that concussions remain an overly significant issue in sports, with kids fighting to play on despite being at severe risk, because "that's what the tough guys do. They shake it off and keep playing."

If you cannot or don't want to accept these realities that's fine, and for sure I'm going to stop trying now to explain them to you as I am fairly sure people must be tiring of this game. At the same time I do hope sometime soon you are able to grasp the things you cannot see now, in a way that will make you a better pilot, to the benefit of your passengers and crew. As well that you will stop making the tiresome argument that you could have done it just fine and the crews obviously should have been able to as well if they had simply followed your advice and FLOWN THE AIRPLANE!!

Warm regards,
dce

[737 Driver]

.

Sorry, fell into pilot speak. Let me translate.


Turn off the magic, :: The only (documented) way to do this was using the trim cutouts, which they did do.

By "magic", I am referring to the automation. Turn of the Flight Directors, disengage the autopilot and autothrottles. BTW, these are the first steps to the Airspeed Unreliable memory items.

set the pitch, :: the were pulling the whole time with little change in displayed pitch, some oscillations after trim cutout.

If the crew had used the UAS procedures, 10 degrees pitch would have been the appropriate target. Pitch control was effective until the runaway event. The reason the Captain had trouble with pitch control was because 1) he did not actively trim against MCAS, and 2) they cutoff the electric stab trim only after the aircraft was severely out of trim.

set the power, :: Crew left it at takeoff, speed reached and settled at near/just over VMO after trim cutout.

Yes, we are aware. There was no attempt to change the power setting after liftoff. "Set the power" does not mean "Leave the power where it is." It means "SET THE POWER," as in put your hands physically on the power levers and set an appropriate power setting. UAS procedures call for 80% N1, but frankly anything between 80 and 90% would have probably been fine for their conditions as long as they also maintained the proper pitch attitude.

monitor the performance, :: don't know enough to comment, other than noticing speed,

In the domain of instrument flying, there are "control" instruments and "performance" instruments. The basic control instruments are the attitude indicator and the primary power setting instrument (N1 on the 737). The performance instruments are things like airspeed, vertical velocity, altitude, heading. You manipulate the aircraft to establish certain parameters on the control instruments, and then you cross-check the performance instruments to see if the aircraft is reacting as you wish. If the aircraft's performance is not to your satisfaction, then you readjust on the control instruments and re-check the performance instruments. For example, if you wish to climb and the aircraft is not climbing, you increase the pitch and/or power and then you go back and see if you are now climbing (while also keeping an eye on the airspeed).

It also means that if you are OVERSPEEDING THE CRAP OUT OF THE AIRFRAME, you need to do something about that, too.

Hence the mantra, set the pitch (control), set the power (control), monitor the performance.

but they may have not have had confidence in instruments.

This statement really is a bit of a reach.

trim the aircraft, :: One has to believe they were trying once cutout, may have wasted some time if only right switch was selected in mistaken belief that manual electric would still be available as on NG.

The "trim the aircraft" part came way, way before the point that they flew themselves into a corner. Yes, you can put this aircraft into a state that even Buck Rogers couldn't extract it. There was no reason to let MCAS trim as far as it did. The yoke trim switch trumps MCAS every single time. Failure to trim, pure and simple.

move to a safe altitude. . :: require pitch control, although they were gradually climbing until the end.

Pitch control would have been available to the Captain if he had simply used the power of his left thumb to trim the aircraft. He did not. The rest is history.

[737 Driver]

If you cannot or don't want to accept these realities that's fine, and for sure I'm going to stop trying now to explain them to you as I am fairly sure people must be tiring of this game. At the same time I do hope sometime soon you are able to grasp the things you cannot see now, in a way that will make you a better pilot, to the benefit of your passengers and crew. As well that you will stop making the tiresome argument that you could have done it just fine and the crews obviously should have been able to as well if they had simply followed your advice and FLOWN THE AIRPLANE!!

Warm regards,
dce

Okay Wonkazoo, you win. I humbly concede. I guess we will all have to accept that any pilot can freeze up at any moment, people will die, and there's nothing to be done. There's no way to train, no way to learn, no way to improve, no way to avoid certain death for some uncertain number of people. The best we can hope for is that someday someone will invent the perfect aircraft and thus be able to remove the imperfect pilot from the equation altogether.

Excuse me if I choose not to live in that world.

[gums]

Salute!
Thanks, Wonk...... well put views and axioms for the pilots and wannabe pilots here.

I am sure that more than one pilot reading all this crapola would have "survived" the scenarios we are examining. But not all. I will go so far as to assert that the Lion Air preceding flight crew had not a clue about MCAS and "lucked out" after getting tired of screwing with the uncommanded trim. The actual notes we saw in our Lion Air thread ( before 737 joined the forums) even stated, "STS running in reverse". That doesn;t sound like someone who knew about MCAS. Especially since the stick shaker was activated and the pilot prolly associated that with a high AoA - you know, a stall warning.

I also like one contributing pilot here that claimed the best thing to do initially when something weird happens is to wind the clock. I am sure the old farts remember that sucker right in front on the intstrument panel. Pressing the "stopwatch function" was the last thing you did before releasing the brakes, huh?

Oh well, maybe Boeing will eventually decide to correct the plane's basic aero characteristics and not add a kludge on top of another. Too many old wiring diagrams and connections, ya think?. So time to do a clean sheet design for all the electronics and try vortex generators, nacelle slots, or something to keep most of the model's production tooling but correct the aero.

Gums sends...

[Sucram]

Okay Wonkazoo, you win. I humbly concede. I guess we will all have to accept that any pilot can freeze up at any moment, people will die, and there's nothing to be done. There's no way to train, no way to learn, no way to improve, no way to avoid certain death for some uncertain number of people. The best we can hope for is that someday someone will invent the perfect aircraft and thus be able to remove the imperfect pilot from the equation altogether.

Excuse me if I choose not to live in that world.
Hes not saying "theres nothing to be done", hes saying people may react in a way to extreme stress that degrades their actions for a period of time. That reaction is obviously undesirable but unfortunately it may happen to anyone including you 737 driver, me or any other pilot, even if you think thats an impossibility.
It is a positive thing however that we are totally confident that we can deal with such situations effectively even though that might not turn out to be the case if we are unlucky.
In the light of this I think it is very wrong we criticise pilots for making mistakes under stress, yes learn from those mistakes definitely but dont ever think youd never ever make them yourself.

[wonkazoo]

Okay Wonkazoo, you win. I humbly concede. I guess we will all have to accept that any pilot can freeze up at any moment, people will die, and there's nothing to be done. There's no way to train, no way to learn, no way to improve, no way to avoid certain death for some uncertain number of people. The best we can hope for is that someday someone will invent the perfect aircraft and thus be able to remove the imperfect pilot from the equation altogether.

Excuse me if I choose not to live in that world.

It shouldn't be surprising that you see this dialogue as something that must be won or lost given what you have written.

Sadly it isn't about winning or losing, its about enlightenment and using knowledge to alter future outcomes. (As opposed to continuing ancient tropes while simultaneously ignoring and exculpating the individual(s) who were really at fault for setting the cheese in motion in the first place.) If you put a hundredth of the energy into picking apart the engineering staff, legal staff, management staff etc at Boeing, and the certification process as overseen (ahem) by the FAA I would be more impressed, not to mention you might have a positive impact on the actual root causes for the entire chain of events.

And the next 737 model you climb into might end up being properly engineered and certified as a result, which I would think would be a happy outcome for you given your profession.

Warm regards,
dce

[737 Driver]

However I am seriously wondering what's going on here and thought it worth pointing out to the population at large.

Regards,
dce

A tad conspiratorial if you ask me, but that's just one pilot's opinion. I don't think powers that be give much a hoot what the participants on this forum think regarding the design (or mis-design) of aircraft, lack of oversight, greed of corporations or whatnot. I suspect that in their eyes, we're just the rabble.

What is going on is I took an interest in these events since I do happen to operate this aircraft, and I came here among other places looking for information. Feel free to go back and look at my earliest posts. Yes, I like a good debate, but I have also tried to pass along relevant information regarding the 737 systems since there were obviously some non-pilots and non-Boeing folks wandering off into the weeds. Along the way, however, I also noticed a definite trend here of throwing bricks across the fence without much in the way of serious introspection. Let's just say I have a thing about intellectual consistency.

I've made no bones about where I think the problems lie, and I've noticed that no one seems to contradict me when I aim my displeasure at Boeing, or the FAA, or the airlines, or anyone but a fellow pilot. Why is that?

Are pilots that infallible? Do we have no room for improvement? Can we not honestly admit our errors and seek to do better? It's perfectly okay to say Boeing fracked up, but we dare not consider that a fellow aviator did as well? I just don't see the logic in that.

You can't fix a problem until you admit a problem exists. Continuing to pretend that there weren't serious lapses in airmanship, that there is nothing that can be done to prevent such future lapses, will do nothing to save future lives. As I've said many times, we aren't going to fix Boeing's issues, or the FAA's, and probably not the airline's (though we have a wee bit more leverage there). We can make a go at addressing ours. Assuming you think that saving lives is a worthy pursuit, of course.

Your choice.

[737 Driver]

Anyway my apologies for the now-deleted post- it didn't further any dialogue and that makes it in the end a wasted effort all the way around.

dce

Apology sincerely accepted.

Yes, I know I come across strong (I would say passionate), and my words may fall harsh on some ears. Call it an attempt to shake some folks out a sense of complacency. Fate may be the Hunter, but we don't have to be a passive prey.

[wetbehindear]

An ancient voice from Paros; We don't rise to the level of our expectations, we fall to the level of our training.

[wonkazoo]

Apology sincerely accepted.

Yes, I know I come across strong (I would say passionate), and my words may fall harsh on some ears. Call it an attempt to shake some folks out a sense of complacency. Fate may be the Hunter, but we don't have to be a passive prey.

Hahahahaha!!!

Sadly both my dad's copy and the first I stumbled on to twenty years ago are in boxes right now so I have to work off memory. But this line, paraphrased though it is will still resonate: "The default is pilot error, because no investigator is going to admit that the best they could come up with is that God unzipped his fly and urinated on the pillar of science..."

This forum is the place for passion, unlike your office, where (I think we both agree) calm reason must rule the day. Even if, as I argue, both calm and reason might occasionally be lost...

Cheers-
dce

[L39 Guy]

Wonkazoo,

I have enjoyed your contribution to this discussion, particularly your first post, but I think you are offside with this post. 737 Driver is doing an exceptional job of articulating what a lot of us professional pilots both on this forum and elsewhere think about this whole MAX affair: MCAS needs to be tweaked (although fundamentally there is nothing wrong with a single sensor device that prevents a stall but intervening in the flight controls like numerous other aircraft), the industry (manufacturers, airlines, CAA's, pilot unions) needs to have a serious look in the mirror as they have been whistling past the graveyard way too long with poor training and over reliance upon automation, etc.

In the final analysis, however, the professional pilot who knows how to fly an aircraft with all of the auto stuff turned off and with bells and whistles blaring has to be able to gain and maintain control of the aircraft. If any of the MCAS accident crews had done that we would not be having this discussion; in the Lion Air incident the day before the fatal one, the crew did, in fact, do the UAS drill (unlike the crashed aircraft cases) and that gave them time to assess the situation and the aircraft control to trim the aircraft, although it is unforgivable that a jump-seating, B737 rated pilot from a different airline had to tell them to turn the stab trim off - that tells me lots about Lion Air's training that 0 of 4 pilots could recognized a stab trim runaway.

Unlike your harrowing experience with the broken control cable for which there is no published, let alone simulator trained procedure, there are procedures for the MCAS event. First, the UAS which is a pretty simple emergency even with bells and whistles blaring - auto stuff off, 10 degree pitch, 80% power. Neither of the fatal aircraft crews did that; the recovered aircraft crew did. Is it a coincidence that the crew that did the drill survive and the others that didn't did not? That should tell everyone something. And remember, the stab trim problem did not manifest itself until after the flaps were raised minutes later.

A stab trim runaway too is a published procedure for not just the B737 but any aircraft with electric trim - fly the aircraft, trim as necessary and if that does not work turn off the electric trim and revert to the backup trim (mechanical in the case of the B737, electric in the case of many other aircraft including the B767, B777 and B787). I haven't flown the B737 for 15 years but having done lots of hand flying with it (it had a very basic Sperry autopilot) one learned how to trim including using continuous trim particularly during flap selections; judging by the lack of continuous trimming by the pilots (but intermittent bursts instead according to the FDR printouts), this tells me that they lack the basic hand flying skills likely because they have spent most of their lives as Children of the Magenta Line, i.e. autopilot cripples. This ties in with my earlier comment on this post as well as one a week or two ago that the industry has to do a rethink of the notion of not hand flying and allowing those hands and feet skills to atrophy. I am sure that you would agree that in your harrowing experience it was your hands and feet skills that saved your bacon not an autopilot.

I am not going to repeat the rest of the analysis as that has been beaten to death on this forum but I, as a 36 year/26,000 hour professional airline pilot who also taught flying for many years, wholeheartedly agree with 737 Driver. If it is of any value, when me and my flying buddies discuss this over coffee we have 100% agreement that this is an entirely manageable situation - we are all ex B737 drivers too. As unpleasant as it is to criticize someone who is no longer on this planet and is unable to defend themselves, these accidents scream "pilot error" for not fulfilling their role as the last line of defense in the Swiss Cheese model.

While you question 737 Driver's credentials, I would be interested in the credentials of those who keep arguing with him - what, if any, flying experience do they have? How much professional flying experience? How much B737 time? If the consensus of my coffee buddies is any gauge, I would think that the majority of professional pilots would agree with myself and 737 Driver that one has to fly the aircraft first then deal with the emergency, particularly since nothing is on fire nor are any pieces falling off the jet. And dealing with emergencies with bells and whistles going off is part of the job for which one has to be trained to overcome in order to focus on flying the aircraft, solving the problem and getting the aircraft back on the ground.

[wonkazoo]

Having been playfully reminded of uncle Ernie I went online to try to find the quote I posted above. I failed, but there are a few more which I did find, and which are wise beyond their years.

Regarding the hidden MCAS:

The emergencies you train for almost never happen. It's the one you can't train for that kills you.

And referencing many of my posts above, and why the pilots need to be cut a ton of slack:

Fear is the afterbirth of reason and calculation. It takes time to recuperate from fear...

Finally this:

Electronics were rascals, and they lay awake nights trying to find some way to screw you during the day. You could not reason with them. They had a brain and intestines, but no heart.

A good ending to this night for me. I need to go find the box with Fate is the Hunter- it's been more than a few years and I miss it dearly...

dce

[wonkazoo]

L39 Guy-

I will respond to your thoughtful post tomorrow when I have time.It has been a long weekend and I cannot do it justice tonight. Thank you for your understanding-

[L39 Guy]

No problem and that was a gracious and class act to retract that post.

[formulaben]

Hahahahaha!!!

Sadly both my dad's copy and the first I stumbled on to twenty years ago are in boxes right now so I have to work off memory. But this line, paraphrased though it is will still resonate: "The default is pilot error, because no investigator is going to admit that the best they could come up with is that God unzipped his fly and urinated on the pillar of science..."

This forum is the place for passion, unlike your office, where (I think we both agree) calm reason must rule the day. Even if, as I argue, both calm and reason might occasionally be lost...

Cheers-
dce

Thank you for that...somehow invoking Ernie Gann makes me feel like we're all somewhat on the same page. Indeed, I plead guilty to being passionate, perhaps overly zealous about airmanship (or perhaps lack of it) but let's all agree that for most of us here it's for the right reasons: lives are on the line. We owe it to them to be over-prepared if we are the ones in charge up front and the last line of defense.

Goodnight.

[Sucram]

although fundamentally there is nothing wrong with a single sensor device that prevents a stall
Not so sure about that on an airliner, I think Airbus put 3 AOAs on their aircraft for a good reason

[formulaben]

I agree. And if I wasn't clear previously, Boeing clearly screwed the pooch, but I still believe that advanced airmanship (e.g. ATP level) should have prevented a complete loss.

[Sucram]

but I still believe that advanced airmanship (e.g. ATP level) should have prevented a complete loss.
I wouldnt really like to make a judgement on that before the final report comes out, but it is of course a possibility.

[TehDehZeh]

I agree. And if I wasn't clear previously, Boeing clearly screwed the pooch, but I still believe that advanced airmanship (e.g. ATP level) should have prevented a complete loss.
The question has to be the following. From 1000 randomly selected 737 crews, how many stuff it into the ground. Mind we are starting from 2 out of 3.
Had the planes been NGs with the same failure, AOA failed high on PF side on rotation), how many would have stuffed it into the ground? (I hope the answer is 0.)
Is the increase in this number acceptable and why was it allowed to increase?

[yanrair]

Wonkazoo,

I understand your position, and I fully support what you say about the need to hold the manufacturers, regulators and airlines accountable. However, I guess we will have to just agree to disagree on how much control the crews had on the outcome.

To me, the great tragedy of these two accidents is not in the complexity of the malfunction, but rather in the simplicity of the appropriate response.

Since my very first days as a student pilot, one primary commandment has been repeated over and over and over again. This commandment applied to all operations, normal and otherwise. Following this commandment may not always save the day, but disregarding it will almost always lose it.

So I'll say it again and again, for as long as it takes: FLY THE AIRCRAFT, first, last, and always.

For all situations, for all malfunctions, for all weather conditions, for all regimes of flight, some pilot must be actively monitoring, and if necessary, actively flying the aircraft. Whenever there is undesired or unexpected aircraft state, the pilot's first and most important priority is NOT to figure out what it is going wrong. The pilot's first priority is to FLY THE AIRCRAFT. Set appropriate attitude and power, monitor the performance, trim as necessary, adjust as appropriate.

In all of the discussion of these accidents, there has not been a single shred of evidence that the primary flight controls or trim were not responding to pilot inputs. There has been no credible argument that if the pilot flying had simply set a reasonable pitch attitude, set a reasonable power setting, and trimmed out the control pressures, that the plane would not have been flyable. The fact remains that in the heat of the moment, these crews forgot or disregarded the first commandment of aviation - FLY THE AIRCRAFT, first, last, and always. WHY they forgot and what corrective measures can be taken to train future crews should certainly be part of a serious post mortem, but we cannot remain in a state of denial regarding what happened.

Sadly, no matter how many times this commandment is repeated, and tacitly acknowledged by just about every pilot, we still seem to have difficulty applying it in practice. Any professional pilot here likely has access to various incident/accident reports. We can read the narratives and easily determine in which cases there was someone actively monitoring or flying the aircraft, and in which cases they were not. Fortunately, most of the "not's" do not wind up as a smoking hole somewhere, but it is still somewhat distressing how often the first commandment is forgotten.

FLY THE AIRCRAFT, FLY THE AIRCRAFT, FLY THE DAMN AIRCRAFT
737 driver
you are saying what I’ve said since the beginning. Someone just said we need a plane that don’t go wrong. Dream on.
This ref QF72 is interesting. 65 complex faults. ALL aural warnings going off at once. Crippled (clearly not) aircraft.
Safe landing. FLY THE PLANE. PITCH POWER. TREAT WARNINGS WITH CAUTION IF THEY DONT APPEAR VALID Use excellent training and CRM to overcome the unexpected.
on takeoff with correct pitch/power/rate of climb/ groundspeed you are safe even if every aural and visual computer generated warning is sounding simultaneously. You’ve got to be trained to cope with that.
AF477 wasn’t. Many more. My concern is not the avionics although clearly MCAS Needs a Mk2 version without the glitches we know about. It is that we may have literally thousands of younger pilots already out there and in the pipeline untrained for the totally unexpected.
https://www.abc.net.au/radio/programs/rhiannapatrick/richard-de-crespigny/10337426

[GordonR_Cape]

The pilot bit is only one element of the issue. Whichever way you look at this, MCAS was a fix to a problem generated by the manufacturer trying to squeeze the last drop out of an airframe designed before I was born. The fix was, at best, a second rate solution which transferred an additional element of hazard management to the pilots; the expectation was that pilots would be good enough to handle the event. Shuffling risk down the line - hmmmm.

An uninformed question (sorry, only 36 years and 22,000 non-Boeing hrs) - how often has the 737 flavour of aircraft had a trim runaway event, how is it manifested (other warnings/cautions) and at what rate does the trim runaway?

Just my wild speculation, but there are several orders of risk:
1. How many times has runaway trim actually pushed a B737 into the ground? Zero.
2. Electromechanical switches are the most likely component to get stuck in the on position. Given that there are two adjacent thumb switches on the B737, and both have to be active, this seems like an extremely low flight risk.
3. Autopilot software malfunction? Turn off autopilot.
4. Electrical wiring and other faults? Unknown.
5. MCAS? 2 out of 3.

[jan99]

If the Lion Air crew and the Ethiopean crew had saved their days as recommended, would MCAS still be flying now?
If so, would that be a happy state?

[safetypee]

Cows ‘Shuffling risk down the line -’ :ok:
Cows, Gordon,
Conventional risk is judged on past outcome, probability vs severity.
‘Future’ risk (certification) has to be judged on the likely-hood of a failure (system safety analysis). If trim can runaway however unlikely, then experts judge of the severity of outcome - manufacturer and certification.

Historically, the mitigation for trim runaway in the 737 appears to have been based on pilot recognition and intervention - inhibit then use manual wheel trim, thus reducing the outcome severity (ex 707 procedure?)
It also appears that the possibility extreme out of trim conditions was recognised, where the tail forces exceed those which allow manual trim. Thus there was an additional procedure requiring large, high stick force elevator inputs to raise the nose, then releasing the elevator input (adverse load), thence the reduced tail load enables manual trim. (To what extent was this flight tested)

The assumptions and procedure appear to have been carried forward for later 737 variants; assuming that certification validated these against aircraft aerodynamic and engine changes (and smaller trim wheel - NG).
This process appears to have further extrapolated for the MAX, but again the extent of certification checks on the effect of (significant) changes is not known.

The outcome of recent accidents suggest that the assumptions relating to large out of trim conditions in the MAX are inappropriate - recognition and intervention (were these aspects considered, checked, or flight tested in the MAX).
Thus the risk associated with trim runway in the MAX appear to be significantly higher that originally judged.
Reviewing the MAX trim system might conclude that runaway is an unacceptable failure mode where recover depends on human intervention; these aspects are independent of MCAS malfunction or modification.

[PerPurumTonantes]

Wonkazoo,

737 Driver is doing an exceptional job of articulating what a lot of us professional pilots both on this forum and elsewhere think about this whole MAX affair: MCAS needs to be tweaked (although fundamentally there is nothing wrong with a single sensor device that prevents a stall but intervening in the flight controls like numerous other aircraft)

Rubbish. I have 21 years in safety related systems including design and certification and you NEVER, NEVER use a single fallible input to drive a safety critical system. And then to give it full authority driving a critical control surface, allowing it to trim full down? Breathtaking incompetence. Also, you ALWAYS design to fail-safe. This doesn't mean what most people think. It doesn't mean it will never fail. It means it will fail in a safe state. AOA disagree is an absolute obvious failure and yet MCAS failed in the most unsafe state that it could possibly have.

A 16 year old electronics student with a week's training in safety related systems design would have done a better job.

[PerPurumTonantes]

these accidents scream "pilot error" for not fulfilling their role as the last line of defense in the Swiss Cheese model.

Just like a goalkeeper who dives the wrong way during a penalty shoot out. Last line of defence and he failed. Clearly should have trained better.

Any pilot who looks at the FDR tapes in detail and doesn't get a shiver going down their spine, and a feeling in the back of their mind "yep, on a bad day, that could have been me" is either genuinely a superhero or has an overestimation of their own abilities. Which is just as dangerous as low abilities.

[Cows getting bigger]

Pilots - last line of defence and Swiss Cheese.

L39 et al, I’m a couple of hours/years short of your experience but my personal experience is that we are not an exceptional line of defence; there are a number of holes in our particular slice of cheese. So, whilst I get paid to be the goalkeeper, there is huge amounts of evidence to prove that I will never keep a clean sheet.

Yep, Lion Air guys could have gotten lucky, and the Ethiopian guys may have done better. But by introducing a half-baked solution like MCAS, Boeing made a pretty shocking back-pass to the goalkeeper. Personally, I’ll be quite happy if in my remaining 10 years or so, all I ever have to do is encourage the defence and mid-field such that I never have to make another save.

Dare I say it, but the differences between A & B philosophy really show here. In the early days of A, I was like many pilots - dubious and wary of automation. Over a generation of flying later we seem to have got our head around they fact that HAL(A) has matured, is now rather good at his job and, generally speaking, our side of the house only gets into trouble when we ignore HAL(A). Meanwhile, HAL(B) appears to still be at school and capable of having hissy-fits, just like my teenage daughter. :)

[Droop Snoot]

If the Lion Air crew and the Ethiopean crew had saved their days as recommended, would MCAS still be flying now?
If so, would that be a happy state?

Yes.
No.

From the response of all involved, the system "requires" at least one crash to get substantive action. In this case, it took 2.

[KRUSTY 34]

Because the airplane ended up in a smoking hole?

Based on everything I’ve read, I would say that these pilots were frantically trying to fly their aircraft, but MCAS had other ideas!

[meleagertoo]

Coverage released on Apr 16th:

On Apr 11th 2019 The Aviation Herald received a full copy of the Flight Operations Manual (FOM), Revision 18B released on Nov 30th 2018, which is currently being used by Ethiopian Airlines (verified in April 2019 to be current). Although Boeing had issued an operator's bulletin on Nov 6th 2018, which was put into Emergency Airworthiness Directive 2018-23-51 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/eff7ed6468ccd134862575e000837739/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf) dated Nov 7th 2018 requiring the stab trim runaway procedure to be incorporated into the FOM ahead of the sign off of this version of the FOM (the entire document is on file but not available for publishing), there is no trace of such an addition in the entire 699 pages of the FOM.

...
...
It turned out, that only very cursory knowledge about the stab trim runaway procedure exists amongst the flight crew of Ethiopian Airlines even 5 months after the EAD was distributed.
...
...

Leaving aside for now the vexed question of Boeing's engineering solutions, something few of us as pilots are really well versed in, it seems to me that the crux of the Ethiopian accident is going to centre on the chilling lines in bold above.

The Indonesian accident was in a way more understandable because of the startle factor despite the unbelieveable precursors to it on previous flights and the standards involved there (which are a completely seperate can of worms) but they should have caused global awareness of the problem very quickly. And did. Mostly.

Focus on operating procedures at Bishoftu will eventually coalesce arond the matters highlited above (if indeed they prove true) but Avherald has a pretty good reputation for sound info.
As I've asked before how can it be possible for two professional pilots on a type with a known and highly public failure mode to appear not to be aware of it's symptoms when it occurs to them? Are these guys hermits with no exposure to global media, internet or crewroom discussions? What the heck else was their 737 crewroom discussing in the months after LionAir? It doesn't seem possible pilots could be so out of such an important and contemporary loop. Or does Ethiopian really exist virtually isolated in a world of it's own?

Worse - the failure of the airline to publish Boeing's amendments and advice. That is a FUBAR of truly epic proportions - unless that sort of thing isn't regarded locally as a FUBAR, but just the way Ethiopian does things...

Worse still, if true, the apparent lack of awareness appears not restricted to the accident crew alone but is shared by many of their colleagues. Is this a cultural thing perhaps?

What this all seems to boil down to is chronic and unrecognisably bad procedures in Ops standards in not one but two airlines. The Human Factors people are going to have a field day over these 'cultural' issues here - be they company or national, which is increasingly looking like one of, if not the major player in both accidents.

[737 Driver]

.

Okay, a lot of ink got spilt yesterday, and I'll also offer my apologies to anyone offended by my admittedly passionate approach. But is has been passion with a purpose. In the interest of moving the conversation along, I would like to more explicitly address a subject that I've only touched on so far.

There are those among us who believe that, when presented with sufficient novelty and distraction, it is completely understandable for an aviator to misdiagnosis a problem and not apply the proper corrective action. After all, we are only human, and all humans are fallible. I really don't have a problem with this general concept, but I strongly disagree that it is a problem beyond remediation.

Let me start with an observation. When the stick shaker went off, the Ethiopian Captain did not turn into a formless lump of clay. He actually did fly the aircraft after a fashion. He manipulated certain controls and he provided directions to the First Officer. I think it is worth looking carefully at what he actually did - rotate, climb to 400', engage the autopilot, continue climb to 1000', retract the flaps, contact ATC, request a vector. If I presented this sequence of actions to you without any preamble as to place or time or aircraft condition, what does this look like? If you said a normal takeoff profile, go to the head of the class. I humbly submit that, when all was going to **** and the Captain was uncertain as to what was going on, he defaulted to his training. Unfortunately, he defaulted to the wrong training.

Let's consider for a moment aircraft reject procedures. Everything is fine up to V1, continue the takeoff. Certain things happen prior to V1, not only reject the takeoff, but reject the takeoff with a set of aircraft-specific actions that must be accomplished in a timely manner. Please read that sentence again. There are at least two "default modes" of operation present in any takeoff (more if you wish to count emergency specific actions like Engine Failure). Which default mode the pilot selects makes all the difference in the outcome.

Just as the "continue the takeoff" mode would be inappropriate with an Engine Fire light prior to V1, the "reject the takeoff" mode would be inappropriate with a Master Caution/Anti-ice light once above 80 KIAS (at least it would be on the 737). For a pilot transitioning from single-engine to multi-engine operations, this is a whole new realm of experience that does not come naturally. (Those of you who have screwed this up in the sim, please raise your hands. :O) The key to successfully training for this maneuver depends on repetitive practice (procedural memory) with a particular focus on the appropriate triggers.

What I am suggesting is that one of the ways out of the conundrum presented by the Ethiopian and Lion Air accidents is to first acknowledge that there really was a "default mode", a set of aircraft-specific set of actions that if accomplished in a timely manner, would have changed the outcome. Please read that sentence again. The default mode to which I refer is the simply the one that I have been repeating ad nauseam: Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude.

Perhaps some of our gentle readers are starting to clue in why I keep repeating this phrase. It is because when you go to bed at night, I want you to be thinking the words, "Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude." I want you to be thinking about these words when you get up in the morning, when you have a cup of coffee, when you are taking a dump, when you are driving your automobile. I want you to think about these words when you are in the sim or when you are "chair flying" a scenario. I want these words to become your mantra. Most importantly, I want you to be thinking these words for every takeoff, every landing, and truly, for every flight operation. Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. Repetition, repetition, repetition.

Once we've committed these actions to procedural memory, then all we need to do is work out the trigger. We have triggers for rejects, we have triggers for engine failures, we have triggers for emergency descents, we have triggers for all sorts of emergencies. When that trigger presents itself, then a certain set of default actions follow.

Let me suggest an appropriate trigger here. When presented with an unexpected warning, an undesired aircraft state, or a loss of situational awareness and you are unclear as to what you should do next: Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude.

Keep repeating this set of actions until you arrive at a stabilized condition where you can better assess what is going on. This procedure is basically the Swiss Army Knife of our non-normals. When you have no clue as to what to do next, Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. Given what we know of Ethiopian 302, Lion Air 610, Air France 447, and a host of other aircraft accidents, I think it is reasonable to say if the crews had applied this procedure, then there would be a few hundred more people alive today.

Easy to say, hard to do you might respond. Yes, you're right. Hard to do, but not impossible to do.

There was a time in my aviation career when one would be subjected to the whims of a sadistic simulator instructor whose only job was to present you with a host of malfunctions and upsets for which there was only one correct initial response: Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. You did this again and again and again until it was impressed upon you that there will come a time when you really have no clue what is going on and that the only safe harbor was, Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. After some passage of time without sufficient evidence that this was a "cost-effective" use of sim time, this type of relatively unstructured training was replaced with what has largely become a set of scripts consisting of known problems and known answers.

I am suggesting that in the aftermath of these accidents there should be a strong reemphasis at every level of training and operations that, despite all efforts to the contrary, the professional pilot can still be faced with novel and potentially hazardous circumstances that exceed all malfunction-specific training. In those circumstances, when there is no other obvious solution, Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude.

Specifically, our training needs to intentionally incorporate surprise, uncertainty, and ambiguity because that is one of the hazards we are likely to face. Some of us have had the opportunity to train in an altitude chamber where we learned first-hand our hypoxia symptoms so that we could better respond to those symptoms in a timely manner. In the same vein, what is needed is a type of training that repetitively introduces us to our startle reflex so we can better recognize it and respond appropriately. And what is that appropriate response? In the absence of any other clear guidance, Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. I humbly submit if that if the Ethiopian and Lion Air crews had been offered this type of training, then we would not be having this conversation today.

I fully realize that some of us are at airlines that are not going to take this message to heart and will not substantially change their training regimen. In those cases, it falls to the individual pilot to do whatever he can to train himself. Repeat the mantra, chair fly some scenarios, and know that at some future point, you may be presented with the unknown and have no clue what to do. In those cases,Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. This will not fix every possible set of malfunctions, and there will be situations which are truly unrecoverable. Fate is Still the Hunter, but I am hoping we may have learned a thing or two since Ernie Gann penned those words. You can only do what you can do with what you have. However, as long as you have an aircraft that is flyable, you will rarely be wrong if you:
.Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude.

[jan99]

Yes.
No.

From the response of all involved, the system "requires" at least one crash to get substantive action. In this case, it took 2.

In which case the exact quality of maintenance and training at the specific airlines is of limited relevance to the greater scheme.

[DaveReidUK]

On Apr 11th 2019 The Aviation Herald received a full copy of the Flight Operations Manual (FOM), Revision 18B released on Nov 30th 2018, which is currently being used by Ethiopian Airlines (verified in April 2019 to be current). Although Boeing had issued an operator's bulletin on Nov 6th 2018, which was put into Emergency Airworthiness Directive 2018-23-51 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/eff7ed6468ccd134862575e000837739/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf) dated Nov 7th 2018 requiring the stab trim runaway procedure to be incorporated into the FOM ahead of the sign off of this version of the FOM (the entire document is on file but not available for publishing), there is no trace of such an addition in the entire 699 pages of the FOM.

Boeing's Emergency AD says nothing of the sort.

It's not up to Boeing what an airline does or doesn't put in its FOM - the AD refers instead to the Airplane Flight Manual (AFM), where Boeing does have the ability to require changes as the AFM forms part of the aircraft certification.

One might have hoped that Avherald would understand the difference between the two publications.

[Smythe]

Not sure where you are getting those numbers as they don't match what's in my FCOM.

Not about inflight feel, was simply looking at the TO range shown. The range difference says alot about CG.
When it comes down to it, is the average TO set the same on the 738 and 737-800?

[737 Driver]

Was simply looking at the TO range shown. When it comes down to it, is the TO set the same on the 738 and 737-800?

Looking at the illustrations (again, no specific numbers provided), they appear slightly different but not so much that I would be concerned about it. With the new engines, one should expect a difference. The 737 is not the first, nor will be the last, airframe that has been re-engined, and changes to accommodate the new powerplants are inevitable. As long as one keeps the aircraft within its authorized c.g. limits, then there really isn't a problem.

[gearlever]

Boeing Didn’t Advise Airlines (https://www.wsj.com/articles/boeings-enduring-puzzle-why-certain-safety-features-on-737-max-jets-were-turned-off-11556456400)
Boeing Co. didn’t tell Southwest Airlines Co. and other carriers when they began flying its 737 MAX jets that a safety feature found on earlier models that warns pilots about malfunctioning sensors had been deactivated, according to government and industry officials.

[L39 Guy]

Rubbish. I have 21 years in safety related systems including design and certification and you NEVER, NEVER use a single fallible input to drive a safety critical system. And then to give it full authority driving a critical control surface, allowing it to trim full down? Breathtaking incompetence. Also, you ALWAYS design to fail-safe. This doesn't mean what most people think. It doesn't mean it will never fail. It means it will fail in a safe state. AOA disagree is an absolute obvious failure and yet MCAS failed in the most unsafe state that it could possibly have.

A 16 year old electronics student with a week's training in safety related systems design would have done a better job.

Newsflash: the entire stabilizer trim system in the B737 is a single point of failure system - there is only one electric motor, there is only one screw jack and any of these can (and have failed) and that is why there is and has been for the past 50 years a Stab Trim Runaway checklist that disables this single point of failure system and the pilot intervenes and trims the aircraft manually. And, a stab trim runaway Aircraft Nose Down (AND) exhibits the same characteristics as an MCAS failure and send the aircraft hurtling toward terra firma; a stab trim runaway Aircraft Nose Up (ANU) will send an aircraft towards the heavens and a stall combined with gravity will quickly bring it back to terra firma.

There are numerous other systems in aircraft which are single point of failure which require pilot intervention: engine failures, for whatever reason, are one. Pressurization where the motors controlling the outflow valves can fail and human intervention is required, hydraulic systems where if the main system fails certain services are not available (Centre system in the large Boeings as an example).

I can go on and on with other examples of systems in aircraft which are not a "single fallible input to drive a safety critical system". In some cases like an engine failure, there is no possible solution to get around this due to physics so that is why we have trained, professional pilots flying airliners and why there is a separate endorsement to fly multi-engine aircraft. We do not live in a utopian world in aviation so we manage it by education and training.

[MurphyWasRight]

Boeing's Emergency AD says nothing of the sort.

It's not up to Boeing what an airline does or doesn't put in its FOM - the AD refers instead to the Airplane Flight Manual (AFM), where Boeing does have the ability to require changes as the AFM forms part of the aircraft certification.

One might have hoped that Avherald would understand the difference between the two publications.

In any case it does seem the pilots were not as informed as they should have been.

It turned out, that only very cursory knowledge about the stab trim runaway procedure exists amongst the flight crew of Ethiopian Airlines even 5 months after the EAD was distributed. In particular, none of the conditions suggesting an MCAS related stab trim runaway was known with any degree of certainty. In that context the recommendation by the accident flight's first officer to use the TRIM CUTOUT switches suggests, that he was partially aware of the contents of the EAD and reproduced some but not all of the provisions and not all of the procedure, which may or may not explain some of the obvious omissions in following the procedure in full

The entire article is well worth reading also has thoughts on ability to manual trim etc

Crash: Ethiopian B38M near Bishoftu on Mar 10th 2019, impacted terrain after departure (http://avherald.com/h?article=4c534c4a/0045&opt=0)

[formulaben]

.
There was a time in my aviation career when one would be subjected to the whims of a sadistic simulator instructor whose only job was to present you with a host of malfunctions and upsets to which there was only one correct initial response: Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. You did this again and again and again until it was impressed upon you that there will come a time when you really have no clue what is going on and that the only safe harbor was, Turn off the magic, set the pitch, set the power, monitor the performance, trim the aircraft, move to a safe altitude. After some passage of time without sufficient evidence that this was a "cost-effective" use of sim time, this type of relatively unstructured training was replaced with what has largely become a set of scripts consisting of known problems and known answers.


Sadly this sounds like far too many of my friends' airline training protocol. We've all done far too many V1 cuts and single-engine approaches to count yet rarely do we see unique and creative scenarios that are not immediately solved by a checklist procedure. This must change, but I fear that the future trend is toward pilots as systems monitors with high reliance on automation and away from airmanship.

[Just This Once...]

Watching the live news conference from Chicago, the Chief Exec gives me precisely zero confidence that Boeing are on top of this. He cannot bring himself to admit that the MCAS, as designed and fitted, had a major role in the accidents.

[bill fly]

Muilenberg sticking to the party line, while having penetrating comments and questions fired at him.
I agree not much in the way of admission...

[Cows getting bigger]

formulaben - why should you fear such an outcome? Surely our role in commercial aviation is to be as safe as reasonably practicable, whichever way that is achieved? MCAS Mk I was an example of poor automation which then meant a continued, or even increased, reliance on SkyGods. If the automation had been half decent, none of us would be discussing suicidal HAL and the ability of flight crews.

[Dannyboy39]

Watching the live news conference from Chicago, the Chief Exec gives me precisely zero confidence that Boeing are on top of this. He cannot bring himself to admit that the MCAS, as designed and fitted, had a major role in the accidents.
Was quite a staggering presser really.

“The MCAS system met with our design and quality criteria and this was a series of events” or something along those lines.

I find that statement incredible. The arrogance. This was a clearly flawed system which has cost the lives of 300 people.

The question I ask - do you agree that a 737-100 is the same aircraft as a 737-9 in terms of TCDS?

[formulaben]

Cows, you're focusing on the automation, I'm focusing on the pilots...do you want better pilots or Children of the Magenta pilots?

[Richard M]

Many on here seem 'niggled' by 737 Driver's posts. The posts are well written, thought provoking and factual ... but if I were to sum up exactly what 737 Driver
is trying to say, it's simple ..
BOTH PLANES WERE FLYABLE !
There was nothing mechanically/electronically/software wrong that was stopping these planes continuing to fly!! FACT
There was no 'show stopper' !!

[Cows getting bigger]

formulaben, I don't think it's that simple. For sure, I don't want children of the magenta, I see enough of them already. But equally, I think the 'better pilot' nut is far more difficult to crack than writing a more failsafe bit of software. In fact, I would want to know what you think makes a better pilot.

I want safer flying which, with a safety manager hat on, means that all elements of the system are considered. This includes from design, manufacture, training, oversight, flight crew etc. The lot.

If we end-up blaming the pilots and then allowing Boeing to get away with a fudge then we have failed as part of the industry.

[safetypee]

meleagertoo, #4589
‘how can it be possible for two professional pilots on a type with a known and highly public failure mode to appear not to be aware of it's symptoms when it occurs to them?’

You appear blinded by hindsight.
The first symptoms and alerts immediately after takeoff were of low speed, approach to stall, erroneous air-data. The crew managed this situation correctly, concluding UAS.
Note that the alerts and annunciations for UAS are similar, identical to the emergency AD re MCAS except there was no trim activity.

Subsequently, flap retraction, MCAS moved the trim. Previous discussions have considered the salience of trim activity and time required to conclude a failure in an intermittent system.
The combination of increased stick force - ‘fly the aircraft’, and UAS could be interpreted as control difficulties - speed error could affect the feel of the aircraft - as would trim.
Thus the crew required a step change in their mindset to associate the revised situation with MCAS, or at least trim problems and then isolate the trim system.
Surprise, startle; the original problem understood, now its not !

[formulaben]

formulaben, I don't think it's that simple. For sure, I don't want children of the magenta, I see enough of them already. But equally, I think the 'better pilot' nut is far more difficult to crack than writing a more failsafe bit of software. In fact, I would want to know what you think makes a better pilot.

I want safer flying which, with a safety manager hat on, means that all elements of the system are considered. This includes from design, manufacture, training, oversight, flight crew etc. The lot.

If we end-up blaming the pilots and then allowing Boeing to get away with a fudge then we have failed as part of the industry.

For some reason you presume I don't want BOTH better automation AND better pilots. Your original question was why would I "fear such an outcome" and the outcome I was speaking to was pilot RELIANCE ON AUTOMATION. Not automation in general. I'm not letting Boeing off the hook and I'm not against better software/hardware, etc. In this instance I'm speaking about the pilots and the pilots only.

Stop putting words in my mouth.

[Cows getting bigger]

I'm sorry, I didn't think I was putting words in your mouth. My point is that if we are in a safer place with reliance on automation then we shouldn't be wringing-our hands because we may perceive this would be at the cost of airmanship.

[L39 Guy]

Just like a goalkeeper who dives the wrong way during a penalty shoot out. Last line of defence and he failed. Clearly should have trained better.

Any pilot who looks at the FDR tapes in detail and doesn't get a shiver going down their spine, and a feeling in the back of their mind "yep, on a bad day, that could have been me" is either genuinely a superhero or has an overestimation of their own abilities. Which is just as dangerous as low abilities.

First, a question. Are you a pilot and a professional pilot? Your previous post regarding 21 years in safety leads me to think not.

I have read both reports and have imaged them in my mind about what I would do in a similar circumstance. For the part between lift-off to flap retraction when it was solely an unreliable airspeed condition, I thought of the case early in my career when I was an FO on a B737-200 and we got stick shaker immediately upon lift-off (no other bells or whistles). I recall the incident clearly; myself and the Captain looked at each other in surprise, we confirmed that the engines were putting out the expected power (EPR), the attitude of the aircraft was correct and the controls were not mushy...no reason to believe that we were in a stall. The second thought was training we received about UAS in the simulator as I believe UAS was a result of AF447. This time there was bells and whistles (no stick shaker) but again revert to basic flying principles (power and attitude) to get some air underneath you first before troubleshooting but at all times someone flying the aircraft. In fact, the sole purpose of the PF (pilot flying) is to fly the airplane while the PNF (pilot not flying) does the troubleshooting/drill. Note that 0 of the 4 pilots in the accident aircraft did the UAS drill and that the incident aircraft the day before did and survived. That is not a coincidence as they were able to control the speed of the aircraft and were able to manually trim the aircraft.

With regard to when MCAS kicks in, yes, that will get your attention however MCAS is so aggressive (i.e. it is neither subtle nor insidious) anyone that knows how to hand fly an aircraft will immediately sense that something is wrong with the flight controls, pull back on the control column and trim aggressively to return to an in trim condition. And I don't mean little, tiny bursts of trim but holding the thumb switch down and really letting it rip.

Trimming out the control forces is an instinctive and unconscious action that 737 Driver has so nicely articulated that is a fundamental skill that pilots with 5 hours of flying time have. I was an instructor in the RCAF on jets and beginning with the second flight with a student (the first flight was a freebee for the instructor to demonstrate the aircraft including his aerobatic sequence!) we harped on trimming the aircraft. Once the student made trimming instinctive, theirs lives and that of their instructor got a whole lot better. This is long winded way of saying that it is impossible for a trained pilot to a) not trim the aircraft and hence nullify MCAS, and b) not determine that the trim is in a runaway (for whatever reason) and disable the trim using the emergency procedure.

I don't believe that doing what one has been trained to do requires superhuman skills; it is a matter of being trained and being prepared. And by being prepared I mean knowing the emergency drills for the aircraft. Perhaps I am "superhuman" in that regard as I regularly review them, particularly the memory items as the memory ain't what it used to be at 59 years of age. Rather than being superhuman, I subscribe to the notion that a professional pilot should know the memory emergencies for their aircraft. Call me old fashioned.

[safetypee]

737 Driver,
your ‘default training’, choice of action, appears to differ from many pilots.
Consider. Having assessed the situation, choose the action according to that situation; not a rigorous follow SOPs / training without question.

The ‘automaton’ approach - follow SOPs, could favour selection of a procedure before assessment and then making the situation fit that mental model; it stifles wider thoughts and adaptation.
Aircraft are not flown via ‘mantra’, by rote; pilots are well trained, skilful individuals, doing their best in difficult circumstance, why then tell them what to do in ‘every’ situation, where ‘every’ situation is only known to them.

Your pedantic focus on procedure - set power as per standard UAS, could reduced the aircraft’s ability to continue climbing when departing for a hot / high airfield, with potential terrain issues; would this be considered, or just follow SOPs adding risk to an emergency situation.

Lengthy posts #4590, and bolded text does not replace the required, well-considered arguments to support a point of view.

[L39 Guy]

Watching the live news conference from Chicago, the Chief Exec gives me precisely zero confidence that Boeing are on top of this. He cannot bring himself to admit that the MCAS, as designed and fitted, had a major role in the accidents.

I watched the press conference too. He was absolutely correct in saying that this accident, like virtually every other one, is the result of a chain of events. MCAS is not the exclusive cause of these accidents as this lively thread demonstrates. As myself, 737 Pilot and others have been trying to say, MCAS needs work but so does the rest of the industry (manufactures, CAA's, airlines, pilot groups) in terms of pilot training, experience and skills.

Having had dealings with the media before and knowing how they like to twist facts, it would be irresponsible of the Boeing CEO to accept full responsibility for these accidents. MCAS is just one piece of the puzzle.

[L39 Guy]

You appear blinded by hindsight.
The first symptoms and alerts immediately after takeoff were of low speed, approach to stall, erroneous air-data. The crew managed this situation correctly, concluding UAS.
Note that the alerts and annunciations for UAS are similar, identical to the emergency AD re MCAS except there was no trim activity.
Erroneous air data was definitely present in spades but what is your proof of "low speed and approach to stall" were present? Every take-off consists of "low speed"; the question is is whether the engines are continuing to put out the advertised power (94% N1 in the case of ET) and the aircraft is accelerating and/or climbing, i.e. gaining energy. They were and it was.

There was no indication whatsoever of an approach to a stall either as the indicated airspeeds were all increasing and the attitude of the aircraft was normal. We cannot tell from the FDR whether the controls were "mushy" or not. But for argument's sake, lets say it was an impending stall - what is the memory drill for that? Lower the nose to reduce alpha then slowly add power being careful not to let the nose pitch-up too much and re-enter the stall. This drill was not done so take your pick, normal take-off (with no changes in pitch/power) with bells and whistles or an impending stall without doing the stall recovery?

[meleagertoo]

‘how can it be possible for two professional pilots on a type with a known and highly public failure mode to appear not to be aware of it's symptoms when it occurs to them?’

You appear blinded by hindsight. ??? How on earth do you figure that? But something had them blinded, that's for sure.
The first symptoms and alerts immediately after takeoff were of low speed, approach to stall, erroneous air-data. The crew managed this situation correctly, concluding UAS. They never even started UAS! Had they concluded it the autothrust would have been disconnected, speed/pitch/thrust under control and flying reasonably normally, not trudging through more or less normal after t/o actions with no atempt to deal with anything else, even including engaging a/p at 400' with a stickshaker going????
Note that the alerts and annunciations for UAS are similar, identical to the emergency AD re MCAS except there was no trim activity. Having read the AD, Lionair reports and discussions they'd know to be only anticipating MCAS activity at flap retraction. Events and sequence were all but identical to LionAir. I rest my case! How could crew on a type that had just suffered such a well publicised accident not recognise the similarities?

Subsequently, flap retraction, MCAS moved the trim.Re-read last comment above. How was it not blindingly obvious at this point? Previous discussions have considered the salience of trim activity and time required to conclude a failure in an intermittent system.
The combination of increased stick force - ‘fly the aircraft’, which they didn't do, did they? and UAS could be interpreted as control difficulties - speed error could affect the feel of the aircraft - as would trim. I suspect they never looked at the speed, or they'd have made the connection between full thrust, overspeed etc etc. And the mythical 'completion of UAS' would have ascertainied which speed indications were reliable/in error so that's not a sound answer.

Thus the crew required a step change in their mindset to associate the revised situation with MCAS which ought to have been in the forefront of their mindset , or at least trim problems and then isolate the trim system. Go and re-read that line again! This should all have been complete deja-vue! Inexplicable trim problems four months after the last big accident - how can memories be that short?
Surprise, startle; the original problem understood, now its not ! I don't think they understood much at all I'm afraid.


If a whole bus-load of people in your previously bear-free neighbourhood were eaten by bears a couple of months ago in the scariest event your neighbourhood has ever seen and you were wandering home one night - fat, dumb and happy others might quite reasonably question the appropriateness of your low-key mental state. Is it wise under the circumstances? But even with one's attention being on the path if you sudenly hear unfriendly animal noises right behind you do you really think - oh - that sounds unusually large and fierce for a raccoon but instead of doing the racoon drill all I'll do is carry on as normal and maybe throw it some peanuts- and just carry on strolling eyes-front as the thing bellows away behind you? It never occurs to you to have a suspicion about what's actually growling? And when you hit the moonlight where you know it'll attack if it actually is a bear you still just stroll on oblivious no thoughts of bears in your mind at all? - indeed you begin to run which is going to make it bite all the harder? And even when it's chewing your arm off your'e still saying, "nice Rocky, have another peanut?" instead of pulling out your bear-gun because you didn't read the newspapers or talk to the neighbours who all said that would be a pretty good idea under the circumstances? Didn't the fact you were even carrying a bear gun suggest to you that even with a runawway bear chewing your ass it might just be there for a useful reason?

[alf5071h]

Many posters citing weak piloting skills, human error, are biased by hindsight, with further biases of believing that all pilots will think and behave the same way (or as they do - earned dogmatism effect) or as trained. These views also represent ‘fundamental attribution error’ seeking the nearest - in action, or last person in a chain of events - timeline.
In reality many of these issues reflect the same difficulties that the accident crews experienced; how to make sense of the situation, choosing a course of action, and opportunity to act.

Posts suffer similar deficiencies in ‘airmanship’ and ability to ‘fly the aircraft’; unable to understand the current situation, think critically and review what is currently known. This ‘lack of airmanship’ is a weakness in thinking skills or ability to use them wisely; particularly with the wisdom of hindsight. First ‘fly you mind’, then act - only post comments after well considered thought; where thought should is based on skills training and particularly practice of those thinking skills.

Pursuing the ‘blame game’, embedded in ‘responsibility’, might be a self-satisfying generation of individual understanding, but this offers little opportunity to learn due to premature closure, from those who already have the (their) ‘answer’.
Other people in this forum also seek understanding, using a cautious evaluation and review, involving skills of critical thinking, which similarly are core values in airmanship.
If posters are unable to achieve a suitable level of thinking given the enlightenment of hindsight, and the luxury of time and wealth of additional information, then they should heed the possibility that they could take similar deficiencies of thought - airmanship, situation awareness, assessment, and judgement into their flight decks.

[737 Driver]

737 Driver, your ‘default training’, choice of action, appears to differ from many pilots.
Consider. Having assessed the situation, choose the action according to that situation; not a rigorous follow SOPs / training without question.


A careful reading of my posts would indicate that the method I am preaching presupposes that the crew is unsure of the nature of the situation, and as such does not have a default SOP to follow. Certainly, if the crew has correctly identified the situation and malfunction, they most certainly should resort to the appropriate procedure. These accident crews did not. In absence of any other guidance, they flailed around until they lost control of the aircraft. Hence the mantra: When faced with an undesired aircraft state, unknown malfunction, or loss of situational awareness...., well you should know the drill by now.

[safetypee]

L39, no ‘proof’ of low speed awareness, only the reported stick-shake and likely ‘barbers pole’ on the EFIS speed display deduced from the system logic.
The inference from the ‘feel diff pressure’ annunciation was that stick forces would generally increase due to stall warning.
Reference to the FDR, there is an indication of a reduction in pitch after takeoff. There is a significant difference between stall avoidance from an alert of stall warning (stick shake) and the actions required for stall identification, particularly at low altitude immediately after takeoff.


meleagertoo, thank you for a colourful reply.
It is difficult to find any clear point, only cherry picking issues for which none of us have an understanding in relation to what the crew saw or thought.
Generally your approach is that of ‘what was’, opposed to an alternative ‘what could have been’, which could provide the basis of wider understanding and benefit to safety.

[MurphyWasRight]

Thus the crew required a step change in their mindset to associate the revised situation with MCAS which ought to have been in the forefront of their mindset , or at least trim problems and then isolate the trim system. Go and re-read that line again! This should all have been complete deja-vue! Inexplicable trim problems four months after the last big accident - how can memories be that short?
Surprise, startle; the original problem understood, now its not ! I don't think they understood much at all I'm afraid.

If a whole bus-load of people in your previously bear-free neighbourhood were eaten by bears a couple of months ago in the scariest event your neighbourhood has ever seen and you were wandering home one night - fat, dumb and happy others might quite reasonably question the appropriateness of your low-key mental state. Is it wise under the circumstances?

Part of the could be restated as :

Suppose you were a tourist in a country where you had a 'technical' fluency in the language but mainly relied on a 'news for tourists' paper and 'safety guidelines for guests' published by the tour operator in your native language,
You had seen an article in the 'news for tourists" about a a bus-load of people perishing due to the rival tour operator's bus driver making a rookies mistake.
Your tour operator did not update his "safety guidelines for guests' as a result of the prior event.

You then unexpectedly meet a bear despite the safety guidelines stating the biggest animal in the region is a raccoon.

The point is that "everyone knew all about Lion Air' is not a proveable true statement and the AV herald statement re lack of knowledge of update trim procedures bt ET pilots strongly suggests that some did not.

[bill fly]

Many posters citing weak piloting skills, human error, are biased by hindsight, with further biases of believing that all pilots will think and behave the same way (or as they do - earned dogmatism effect) or as trained. These views also represent ‘fundamental attribution error’ seeking the nearest - in action, or last person in a chain of events - timeline.
In reality many of these issues reflect the same difficulties that the accident crews experienced; how to make sense of the situation, choosing a course of action, and opportunity to act.

Posts suffer similar deficiencies in ‘airmanship’ and ability to ‘fly the aircraft’; unable to understand the current situation, think critically and review what is currently known. This ‘lack of airmanship’ is a weakness in thinking skills or ability to use them wisely; particularly with the wisdom of hindsight. First ‘fly you mind’, then act - only post comments after well considered thought; where thought should is based on skills training and particularly practice of those thinking skills.

Pursuing the ‘blame game’, embedded in ‘responsibility’, might be a self-satisfying generation of individual understanding, but this offers little opportunity to learn due to premature closure, from those who already have the (their) ‘answer’.
Other people in this forum also seek understanding, using a cautious evaluation and review, involving skills of critical thinking, which similarly are core values in airmanship.
If posters are unable to achieve a suitable level of thinking given the enlightenment of hindsight, and the luxury of time and wealth of additional information, then they should heed the possibility that they could take similar deficiencies of thought - airmanship, situation awareness, assessment, and judgement into their flight decks.


Unfotunately most people these days want a quick easy solution to life’s complex problems.
You can see it in politics and in daily life. It leads to repetitive emphasising of dogma and it led to Trump.
You can see it in these discussions.
The tragedy is that some of the items of dogma could be valid, if discussed reasonably but can’t be heard in the torrent.

[wonkazoo]

L39 Guy and 737 Driver- I owe you both a reply form last night, but it will have to wait for a bit.

In getting caught up with the thread just now a number of continuations of the theme from teh past week popped up, some in support of your stated observation/opinions and some against. Instead of arguing about them ad infinatum I had a vision of explaining how we aren't necessarily as far apart as it may seem, but also how your view as stated is (IMHO) deeply flawed and unforgiving towards four people who are not here to defend themselves.

My path to enlightenment is actually very easy and short.

Assumption: MCAS is a bastard system (some would say a killer) that was created and installed at the last minute and that provides a stupid feel/feedback control with actual control over the entirety of the horizontal stabilizer's range of movement.

Statement 1: Many professional pilots feel strongly that the primary focus for responsibility (note I said primary, not sole) lies with the airmanship (or lack thereof) of the flight crews who perished. In a narrow window of time they failed to correctly (as in solve the puzzle) answer the challenge they had been presented with, the first time never getting there, the second not getting there until the stab was outside of a previously unknown box that would allow it to be manually rolled back into more usable territory. The follow-on to this statement is that both crashes were the fault of the crews for failing the most basic of tasks- to fly the airplane.

Statement 2: Many of us here feel that there is a deep and very real culpability within Boeing and the FAA for creating such a lethal design. In this case (this is all entirely hypothetical, please work with the suggestion rather than the actuality) an engineer was presented with a problem that needed to be solved. She and her team came up with MCAS. The person responsible for choosing the best course of design knew that MCAS would have a profound impact on the horizontal stab, and they chose to shoehorn it in there anyway. The flight-test crews knew of the system at least and failed to properly review it for (what are now) obvious technical and safety shortcomings. Then, in a further admission that they were pushing the envelope everyone involved at Boeing literally hid the existence of the system from the pilots and operators who would fly the airplane. That person(s) also misled the FAA by informing the feds that the maximum authority that MCAS would have was .6 of a degree, when in reality (and they knew this) it was 2.5 degrees at a whack. In a final insult they said "all you need is an hour with this here tablet-thingy and you will know all you need to know to safely command and fly the MAX series of aircraft!!

With those two statements on offer- and the acknowledgement that there is plenty of blame to go around, the question I have is why are you not focusing on Boeing, the corporate culture that created this monster, the profit-driven betrayal of everyone here, and the fact that they are clearly working to pull a rabbit out of the hat in lieu of actually starting over again- which is what any rational society would require them to do. Yes, we know who the four crew members are, so that makes them easy targets, but if the professionals on this forum are willing to eat their own while looking the other way as Boeing goes about its PR campaign then what does that really say about all of us??

Warm regards-
dce

[gearlever]

Unfotunately most people these days want a quick easy solution to life’s complex problems.
You can see it in politics and in daily life. It leads to repetitive emphasising of dogma and it led to Trump.
You can see it in these discussions.
The tragedy is that some of the items of dogma could be valid, if discussed reasonably but can’t be heard in the torrent.

Very well said:ok:

[Zeffy]

https://www.seattletimes.com/business/boeing-aerospace/facing-sharp-questions-boeing-ceo-refuses-to-admit-flaws-in-737-max-design/


Facing sharp questions, Boeing CEO refuses to admit flaws in 737 MAX design
April 29, 2019 at 10:47 am Updated April 29, 2019 at 1:19 pm

by Dominic Gates
Seattle Times aerospace reporter

CHICAGO — In a dramatic and tense news conference, his first since two deadly crashes of 737 MAX airplanes, Boeing Chairman and CEO Dennis Muilenburg faced sharp questioning but refused to admit flaws in the design of the airplane’s systems.

“We have gone back and confirmed again, as we do the safety analysis, the engineering analysis, that we followed exactly the steps in our design and certification processes that consistently produce safe airplanes,” he said. “It was designed per our standards. It was certified per our standards.”

In the case of the MAX, those processes certified as safe a new flight-control system that was triggered on both the Lion Air and Ethiopian crash flights by a single faulty sensor and then engaged repeatedly to push the nose of each airplane down. Boeing is currently flight testing a software redesign of this system — Maneuvering Characteristics Augmentation System (MCAS).

Yet Muilenburg would not concede that there was anything wrong with the original MCAS design, saying only that the system is being “improved” with the software redesign.

He said airplane accidents are typically due to “a chain of events,” and that “it’s not correct to attribute that to any single item.”

He pointed to actions by the pilots on the two flights, who he said did not completely follow the standard procedure when uncommanded tail movements begin to push the jet’s nose down. He added that Boeing’s system safety analysis of MCAS, a technical document prepared by Boeing during certification of the MAX, depends in part on the pilot making the appropriate response in the case of a system failure.

At the brief news conference following Boeing’s annual shareholder meeting at Chicago’s Field Museum, Muilenburg faced one question after another about flaws in MCAS but repeatedly declined to concede that it was badly designed.

His statements hewed closely to the line he followed on an earnings teleconference last Wednesday, when he said the MAX crashes were not due to any “technical slip” by Boeing during the jet’s design or certification.

He took questions for less than 15 minutes. Finally, after parrying a question about whether he had thought about resigning and a last question about blame for MCAS, Muilenburg walked out grim-faced.

As he strode briskly from the room, many reporters had not been called upon. One of those shouted after him: “346 people died. Can you answer some questions?”

Boeing’s proposed software fix for MCAS ensures the system takes input from two sensors, instead of one. It will activate only once, not multiple times, if the sensor reading remains stuck at a high value. And the power of the system will be limited, so that the pilot can always pull back on the control column with enough force to counteract any automatic nose-down movement.

With that fix, Muilenburg said, the MAX when it returns to service will be “one of the safest airplanes ever to fly.”

During the shareholder meeting, a couple of small stockholders asked more gently worded questions about the MAX crashes.

One older man, who identified himself as an engineer, questioned how MCAS was designed to depend on a single unreliable sensor. A young woman questioned whether oversight by the Federal Aviation Administration was sufficiently independent.

Muilenburg’s response to the engineer simply reiterated the statement that Boeing had followed its long-standing procedures in the design and development of the MAX.

On the need for independent oversight, he said Boeing’s airplane development process includes “non-advocate reviews,” when experts who aren’t on the specific program are brought in to evaluate it.

Security was tight at the shareholder meeting, which was attended by the entire Boeing board. Attendees were screened through airport-style metal detectors and explosives-detecting dogs sniffed at all bags.

The event featured shareholder votes on a series of formal proposals, including one to separate Muilenburg’s dual role as chairman and CEO by appointing a separate chairman, another seeking to ensure that executive pay is not boosted by share repurchases, and another to force more disclosure of Boeing’s lobbying activities.

All these external proposals were given short shrift by the board and none came close to passing.

Outside the museum, a small band of relatives of people who died on the Ethiopian Airlines plane protested in the pouring rain. One sign called for the prosecution of Boeing and its executives for manslaughter.

Tarek Milleron, the uncle of 23-year-old Samya Stumo, who was among those killed, said that Boeing’s leadership “should open up on the chain of events that led to these accidents.”

Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.

[737 Driver]

With those two statements on offer- and the acknowledgement that there is plenty of blame to go around, the question I have is why are you not focusing on Boeing, the corporate culture that created this monster, the profit-driven betrayal of everyone here, and the fact that they are clearly working to pull a rabbit out of the hat in lieu of actually starting over again- which is what any rational society would require them to do. Yes, we know who the four crew members are, so that makes them easy targets, but if the professionals on this forum are willing to eat their own while looking the other way as Boeing goes about its PR campaign then what does that really say about all of us??



Why indeed?

Let me answer a question with a question.

Are you more interesting in bitching or saving lives?

Sorry to put it so bluntly, but really that is what it comes down to. I've already answered this query, but let me state it again. There was a chain of causation in these accidents. That chain consisted of the following:

1. Lapses at Boeing
2. Lapses at the FAA and other certificate authorities
3. At least in the case of Lion Air, lapses in the maintenance/logistics area.
4. Lapses within the airlines in terms of education, training, policies, and culture​​​​​​.
5. Lapses in flight crew member actions

Granted, some may have a different list, but this mine for moment. Now let me ask very pointedly, if the goal is to increase the safety of our operations and prevent future accidents, which item on this list do we, as front line operators, have the most power to effect?

I don't care how insightful or detailed of analysis anyone on this forum could come up with on items 1 thru 3, the chance of it making any difference is essentially zero. It might make you feel better in some respects, but it will not change a thing. Maybe, if the right people are paying attention here, we could have an impact on item 4. However, if the motivation is truly to improve safety and save lives, item 5 is where we ought to spend our time.

As I've said several times already, you can't solve a problem until you recognize a problem exists. I'm sorry if in the course of defining the problem it appears that we are "eating our own," but that is not the intent.

BTW, doesn't it really bug you how Boeing, the FAA, and the airlines try to be all mushy-mouth in saying that they really didn't screw things up? Of course they did!

Why don't they just admit it and get on with fixing their problems?!

That is a very good question indeed.
.

[marie paire]

Groucho Marx words come to mind: "Those are my principles. If you don't like them, I have others".

[DaveReidUK]

Would some one detail these "lapses" at Lion air alongside supporting evidence..

You might want to compare

a) the FDR traces from the penultimate flight

b) what the crew wrote up about it (or, rather, didn't) in the tech log

[DaveReidUK]

oh you mean form an opinion then...

Well yes, I would hope that having compared them, you would form an opinion.

You did ask, after all.

[nyt]

The thing is, there would be no need to discuss any of this if it wasn't for these poorly-trained pilots flying one of the thousands of planes ordered. And SLFs decided (so far) that the ticket price covers the risk of flying with less reputable airlines (which again, is probably better for them than not flying at all to get where they want).
As was stated before by a safety engineer, you can address the current situation by more training for a lot of people (increasing costs hence tickets price), and only reducing the risk by a small margin (HF being what is is). Or you can fix the design at a lower cost for everyone (but Boeing), considering that the current average level of airmanship is sufficient. One could say that given the actual safety record of the industry, it is.

[Alchad]

Why indeed?

Let me answer a question with a question.

Are you more interesting in bitching or saving lives?

Sorry to put it so bluntly, but really that is what it comes down to. I've already answered this query, but let me state it again. There was a chain of causation in these accidents. That chain consisted of the following:

1. Lapses at Boeing
2. Lapses at the FAA and other certificate authorities
3. At least in the case of Lion Air, lapses in the maintenance/logistics area.
4. Lapses within the airlines in terms of education, training, policies, and culture​​​​​​.
5. Lapses in flight crew member actions

Granted, some may have a different list, but this mine for moment. Now let me ask very pointedly, if the goal is to increase the safety of our operations and prevent future accidents, which item on this list do we, as front line operators, have the most power to effect?

I don't care how insightful or detailed of analysis anyone on this forum could come up with on items 1 thru 3, the chance of it making any difference is essentially zero. It might make you feel better in some respects, but it will not change a thing. Maybe, if the right people are paying attention here, we could have an impact on item 4. However, if the motivation is truly to improve safety and save lives, item 5 is where we ought to spend our time.

As I've said, you can't solve a problem until you recognize a problem exists. I'm sorry if in the course of defining the problem it appears that we are "eating our own," but that is not the intent.

BTW, doesn't it really bug you how Boeing, the FAA, and the airlines try to be all mushy-mouth in saying that they really didn't screw things up? Of course they did!

Why don't they just admit it and get on with fixing their problems?!

That is a very good question indeed.
.

My answer to the question would be that apportioning blame is a second order to actually determining the cause/reason the planes crashed. Isn't the one inescapable fact that had those planes been earlier models the dead would still be alive? You can argue that the pilots should/ ought to have been capable of handling the problem that they were faced with, but again in aviation as for cars technology trend towards increased safety. To me a lowly PAX maybe, but one who is still capable of analysing facts, nothing about the MCAS introduction says increased safety, rather a crude fix

[FrequentSLF]

The thing is, there would be no need to discuss any of this if it wasn't for these poorly-trained pilots flying one of the thousands of planes ordered. And SLFs decided (so far) that the ticket price covers the risk of flying with less reputable airlines (which again, is probably better for them than not flying at all to get where they want).
As was stated before by a safety engineer, you can address the current situation by more training for a lot of people (increasing costs hence tickets price), and only reducing the risk by a small margin (HF being what is is). Or you can fix the design at a lower cost for everyone (but Boeing), considering that the current average level of airmanship is sufficient. One could say that given the actual safety record of the industry, it is.
I have an issue with increasing ticket price to cover for more training for a lot of people...the bean counters in few years will come with a way to reduce costs to increase profit, reducing the training costs.
The reputable airlines have "forced" Boeing to come up with the MAX, without SIM training in order to compete with AB. I found very difficult to accept that the issue of SIM training/MAX is driven by ticket prices, reputable airlines are probably enjoying bigger discounts on planes. Delta/American/United have reported multi billion dollars net profit in 2018. Spending 60 million of that profit would allow to purchase 2 SIM (5 million each), and perform 10000 hours of training on them (5000/hour). I do not think will break the companies, unless you are a bean counter, than we got to my first paragraph....

[737mgm]

L39 Guy and 737 Driver- I owe you both a reply form last night, but it will have to wait for a bit.

In getting caught up with the thread just now a number of continuations of the theme from teh past week popped up, some in support of your stated observation/opinions and some against. Instead of arguing about them ad infinatum I had a vision of explaining how we aren't necessarily as far apart as it may seem, but also how your view as stated is (IMHO) deeply flawed and unforgiving towards four people who are not here to defend themselves.

My path to enlightenment is actually very easy and short.

Assumption: MCAS is a bastard system (some would say a killer) that was created and installed at the last minute and that provides a stupid feel/feedback control with actual control over the entirety of the horizontal stabilizer's range of movement.

Statement 1: Many professional pilots feel strongly that the primary focus for responsibility (note I said primary, not sole) lies with the airmanship (or lack thereof) of the flight crews who perished. In a narrow window of time they failed to correctly (as in solve the puzzle) answer the challenge they had been presented with, the first time never getting there, the second not getting there until the stab was outside of a previously unknown box that would allow it to be manually rolled back into more usable territory. The follow-on to this statement is that both crashes were the fault of the crews for failing the most basic of tasks- to fly the airplane.

Statement 2: Many of us here feel that there is a deep and very real culpability within Boeing and the FAA for creating such a lethal design. In this case (this is all entirely hypothetical, please work with the suggestion rather than the actuality) an engineer was presented with a problem that needed to be solved. She and her team came up with MCAS. The person responsible for choosing the best course of design knew that MCAS would have a profound impact on the horizontal stab, and they chose to shoehorn it in there anyway. The flight-test crews knew of the system at least and failed to properly review it for (what are now) obvious technical and safety shortcomings. Then, in a further admission that they were pushing the envelope everyone involved at Boeing literally hid the existence of the system from the pilots and operators who would fly the airplane. That person(s) also misled the FAA by informing the feds that the maximum authority that MCAS would have was .6 of a degree, when in reality (and they knew this) it was 2.5 degrees at a whack. In a final insult they said "all you need is an hour with this here tablet-thingy and you will know all you need to know to safely command and fly the MAX series of aircraft!!

With those two statements on offer- and the acknowledgement that there is plenty of blame to go around, the question I have is why are you not focusing on Boeing, the corporate culture that created this monster, the profit-driven betrayal of everyone here, and the fact that they are clearly working to pull a rabbit out of the hat in lieu of actually starting over again- which is what any rational society would require them to do. Yes, we know who the four crew members are, so that makes them easy targets, but if the professionals on this forum are willing to eat their own while looking the other way as Boeing goes about its PR campaign then what does that really say about all of us??

Warm regards-
dce

Almost 5000 posts later it is clear it doesn't matter what professional 737 pilots will say about this issue. You guys have made up your mind and no facts will get in the way of that opinion. Nonetheless I will give it another try even though what I am about to write has probably already been mentioned several times:

The MCAS system obviously should have been designed better but the press makes it seem as if Boeing knew the system created great risks but they went ahead with it anyway in order to make more profit. That thought in itself is so absurd that arguing with anyone who believes it, is basically pointless. If Boeing had thought these accidents were likely to occur they would have designed the system differently.

What does this MCAS monster as you call it actually do? It lowers the nose of the aircraft by changing the position of the horizontal stabilizer. It doesn't make the wings fall off, it doesn't set the plane on fire... it only moves the horizontal stabilizer. There is a switch on the pilots control column which moves the horizontal stabilizer and it overrides MCAS each time. I know you guys do not want to face it, but it really is that simple. Now if someone is reading this, thinking if it was that simple why didn't the pilots just do it? First of all they did. The Lion Air Captain did it at least twenty times. And the Ethiopian Captain did trim out the MCAS induced movement completely the second time it activated. So we could already talk a lot about why they didn't do it the whole time, then lower the flaps for landing (MCAS deactivates) and land. Aside from the fact that they did use the trim switch a little bit at least. please have a look at Asiana flight 214, Emirates 521, or Turkish 1951. These are only a few examples of flights were pilots failed to do the most basic thing: flying the aircraft. There were other causes as well and in the case of Turkish and Asiana the flights were not stabilized at 1000 Feet which means they should have carried out a go around preventing both accidents even before the mistake of not flying the aircraft (speed control) was made.


What these accidents show you is that pilots will crash aircraft even though it would have been very easy not to. In the case of Asiana and Emirates there were not even any system failures. Why these things happen is a completely different issue and the answers are to be found in the human factors involved when people fly aircraft. The Fact is, planes crash because pilots do not carry out the basic steps involved in flying an aircraft.

Now one important point I would like to make to all the posters with their Skygod and hindsight comments: First of all, it isn't about blaming the pilots. It is about stating facts. If I or others state that the crew did not carry out the unreliable airspeed memory items when in fact Boeing requires a crew to so in the situation they were in, then that is stating a fact and has nothing to do with hindsight or blame. Stick shaker only on one side, several caution lights going on, differing airspeed indications create a very confusing situation. For exactly that reason there are memory items in order to deal with that situation and they must be carried out. This procedure is a life saver because in that situation it is nearly impossible to figure out which system is malfunctioning and what is actually going on. For that reason: AP off, AT off, FD both off, flaps extended 10° pitch 80% N1. This will set the airplane on a safe flight path and you will continue to climb away from the ground. Now you have time to figure out the problem. This is what we are trained for. This is our job. Carrying out these procedures in that situation has nothing to do with being a skygod and pointing out that the crew did not do it doesn't make us armchair pilots with hindsight. If there is an engine fire on take off I carry out my memory items, if there is a rapid depressurization I carry out my memory items. Again this is what we are trained for.

If the crew had done this on any of these flights we wouldn't even be talking about MCAS. I am not blaming the crew when I say they did no do this. The crew is always just a product of the training department and the general procedures of the airline they fly for. For example, in the case of the Emirates crash, the crew wanted to fly a go around. They only pushed the take off/go around button but did not actually move the thrust lever forward in order to increase thrust on the engines. These pilots were not idiots. I can completely understand how this could happen. Normally as long as the automatic thrust control is engaged, pushing the TOGA button will increase thrust. However, shortly after touch down the automatic thrust control is automatically disengaged. Emirates is an airline with procedures that will not allow pilots to fly manually with the flight directors off for example. I can understand how a crew that is trained to rely on automation will not think to actually move the thrust levers and will not check if the thrust is increasing, despite procedures to do so. Basic skills are lost if one does not use them regularly.

The 737 MAX is grounded and will continue to be grounded for a long time because people think the airplane is unsafe. Furthermore the press reported the Ethiopian pilots carried out all the required procedures and yet they crashed. Why are people like me writing on this forum? It simply isn't true that the 737 MAX is inherently unsafe even with the "old" MCAS and it isn't true that the crew carried out the required procedures. That is not my opinion. That is a fact (again why they did not do it is another issue). If the established procedures had been carried out the planes would not have crashed. There was not one procedure done wrong but several done wrong. Each one of these procedures would have saved the aircraft. Carrying out the unreliable airspeed memory items is one procedure. If the pilots do not do this they are already entering an area where they are not flying the airplane according to procedure anymore but even in that case, carrying out the stab trim runaway memory items correctly once MCAS engaged (please stop these ridiculous comments that the MCAS activation cannot be recognized as a stab trim runaway) would also have saved the plane. If the pilots decide for whatever reason to not even do that, they still have the option of just trimming out the control forces each time MCAS activates (basic flying skills). Again when I am stating what they should have done according to procedure I am not blaming the pilots but only stating the facts of what Boeing says pilots must do in these situations and what we are trained for in our manuals and in the simulator. These recommended procedures would have saved the plane and please realize that there was a flight that had exactly the same problems and they did land safely (and they did not carry out unreliable airspeed mem items and also did not accurately carry out the stab trim mem items and still they saved the plane proving there are several options and it is not a react quickly or die situation).

Final comment: In my opinion crews that are not trained well and are lacking basic skills of flying the aircraft due to company policies are a far greater threat to aviation safety than any system design. I believe we still have a long way to go until we will design systems that never fail (if ever). So it will continue to be up to the pilots to save the day when systems malfunction. There needs to be a focus on enabling pilots to do so a lot more than focusing on how MCAS can be improved.

[737 Driver]

My answer to the question would be that apportioning blame is a second order to actually determining the cause/reason the planes crashed.





And my response would be that some people are having trouble seeing that, quite often, these are really two sides of the same coin.

To put it another way, if the accident investigation team determines that one of the primary causes was the poor design of MCAS, would Boeing be blameless?

[maxxer]

Why does the Raytheon uav not have outboard AoA sensors is there a far superior technology already , but maybe more difficult to maintain?

[skwdenyer]

"Southwest Airlines says Boeing didn't disclose it had deactivated safety alert on 737 Max jets"

So says Bloomberg, quoting the WSJ. I shan't copy-paste the article here, and I don't believe I can post a link, but the essence is that SWA are stating that their manuals showed the AOA Disagree alert as being a standard feature, not optional, and that they did not know it was optional until after the Lion Air incident. They're also saying that the AOA Disagree alert was standard fit on the NG.

[Water pilot]

Trimming out the control forces is an instinctive and unconscious action that 737 Driver has so nicely articulated that is a fundamental skill that pilots with 5 hours of flying time have.
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate. You can see Formula 1 drivers adjusting the steering wheel while their car goes airborne, people try to turn on the lights when the power is out, the helmsman will pull on the throttles as the ship with dead engines inexorably heads to crush the wharf, etc. It defies reason that none of the four pilots held the button down to the last.

I don't know what it could be (can you break the switches by pressing too hard on them?)

[MemberBerry]

Are you more interesting in bitching or saving lives?

Have you considered that bitching may save lives? Without extensive "bitching" against Boeing and the FAA from the pilot community, even going as far as being considered "hysterical" by some, the responsible parties at Boeing and the FAA may just conclude that pilots will accept whatever **** system they will come up with and respectively certify, and at some point the public will forget and carry on flying on those flawed machines. How is that a good thing for safety?

I would love nothing more than having all the holes in the layers of cheese patched, including any deficiencies in pilot training. That may require bitching too, not just towards Boeing and the FAA, but also towards the airlines that are extremely reluctant to give the pilots more than a few hours of training, and no simulator training if at all possible.

I think sometimes an attitude along the lines of "I'm mad as Hell and I'm not going to take this anymore" is required to make the responsible parties realize this cannot continue, and fundamental changes must be made. In my opinion that should start with the FAA being given the appropriate budget and independence from political influence to be able to properly regulate both the airlines and the aircraft manufactures, forcing them to "produce" both safe aircrafts and safe pilots respectively.

As a passenger, I will try my best to avoid Boeing aircraft until that actually happens.

[737 Driver]

Have you considered that bitching may save lives? Without extensive "bitching" against Boeing and the FAA from the pilot community, even going as far as being considered "hysterical" by some, the responsible parties at Boeing and the FAA may just conclude that pilots will accept whatever **** system they will come up with and respectively certify, and the public at some point will forget and carry on flying on those flawed machines. How is that a good thing for safety?



I would suggest that if you want to bitch to Boeing, then bitch to Boeing. If you want to bitch to the FAA, then bitch to the FAA (perhaps through your Congressman). I'm pretty sure that neither Boeing nor the FAA are reading these posts. Even if they were, armies of lawyers are firing multi-hundred page briefs across the bow of all the agencies I listed in items 1 thru 4. Anything posted here is a mere fart in a windstorm compared to that onslaught.

[737 Driver]

This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet.

You can find a fairly comprehensive review at the following link which includes some reasonable speculation as to why the pilots did not trim sufficiently during the final moments:

https://www.satcom.guru/2019/04/what-happened-on-et302.html​​​​​​

[Water pilot]

You can find a fairly comprehensive review at the following link which includes some reasonable speculation as to why the pilots did not trim sufficiently during the final moments:

https://www.satcom.guru/2019/04/what-happened-on-et302.html​​​​​​

Thanks for the link, but note that they shrug their shoulders as well:
In any case, it is not clear what prevented the crew from continuing to trim airplane nose up to reduce column forces.

This is something that needs to be figured out, and I hope that Boeing's internal practice is different than their public stance that three independent aircrews (the first crew did not respond properly, either) were not skilled enough to fly their plane. They need to test this scenario to failure in the sim, find the worst line pilots imaginable, the ones quite close to being terminated but still qualified, and put them through this scenario and see what they do. If they can't replicate the scenario, something else is wrong.

Boeing's conclusion that pilots are unqualified to fly the MAX -- and that is their conclusion, and the conclusion of many here -- is at odds with their stance that a 15 minute IPAD session will fix everything. Boeing markets the plane as being flyable by pilots that meet industry standards and either the plane is not flyable by pilots who meet those standards (you can't argue with two crashes in six months) or there is something wrong with the plane. The latter is far easier to fix.

[MurphyWasRight]

Stick shaker only on one side, several caution lights going on, differing airspeed indications create a very confusing situation. For exactly that reason there are memory items in order to deal with that situation and they must be carried out.
...
There was not one procedure done wrong but several done wrong. Each one of these procedures would have saved the aircraft. Carrying out the unreliable airspeed memory items is one procedure
.

Things are never as black and white as one might wish. The ET pilots were not at all perfect but they were also misserved by the system.

This is text from a Boeing UAS flow chart someone posted a while back, not I do not have access to current procedures,although what probably matters as much is what was in effect when the Pilot was trained.
Seems totally reasonable to decide it is false AoA related warning.

AoA sensor failure on Takeoff
If AoA sensor is failed high,stick shaker on failed side will activate on rotation accompanied by IAS/ALT disagree warning flags.

If the pitch power and config are consistent with takeoff and the good side ASI agrees with the Standby ASI,then it is a false warning
There is a side arrow to the side that states "If in any doubt execute the UAS NNC"

The pilot with good side data becomes PF

Land immediately

With a 360 hour co-pilot there may be a reason the Captain retained control, especially with relatively small ASI difference.



And the Ethiopian Captain did trim out the MCAS induced movement completely the second time it activated. So we could already talk a lot about why they didn't do it the whole time, then lower the flaps for landing (MCAS deactivates) and land.
...
...
even in that case, carrying out the stab trim runaway memory items correctly once MCAS engaged (please stop these ridiculous comments that the MCAS activation cannot be recognized as a stab trim runaway) would also have saved the plane.

Note, the times below are from the FDR chart which is hard to read better than a second or so due to ambiguous sloping edges on binary traces.

The first MCAS trim started at 05:40:00 ending about 9 seconds later, this was as the autopilot dropped out after flap retraction.

The pilot only partially unwound the trim at 05:40:15, 5 seconds later the second MCAS input started but was cancelledby sustained pilot trim starting at 05:40:29.
This second trim attempt lasted until the stab trim was cutout.
From the prelim report:
At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First-Officer confirmed stab trim cut-out.

Given that Boeing changed the cutout switch functions on the MAX so that either one disabled all electric trim whereas on NG the right switch disabled automatic trim only it is possible/likely that the pilot was still trying to trim.
Much later the (very sparse) partial transcript has this:

At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54, the First-Officer replied that it is not working.

This supports the idea that they believed they had only disabled automatic trim and manual electric trim should still function.
This difference is not highlighted, or mentioned at all depending on which MAX type conversion powerpoint the crew used.

Bottom line is that runaway trim nnc was executed but they were (apparently) left with an inability to crank the trim wheel.
"Unloading" maneuvers used to be part of runaway stab training but apparently were dropped some time ago.

To anyone contemplating commenting on the emergency AD stating to trim first if MCAS runway:
A: That was buried as a note -after- action items.
B: ET pilots company may have failed to update manuals.

Of course it is tragic that they did not input sustained trim after an apparent last ditch effort where they re-enabled electric trim. I still wonder if some other factor is at work here since almost exactly the same thing is seen at end of Lion Air traces.

There was less than 45 seconds from start of first MCAS trim to loosing all trim capability.

They might have done better had they not followed the runaway trim procedure.

I do totally agree on your points on the state of training and company policy that result in poor confidence in manual skills, this undoubtedly also played a significant role in this accident.

Note I see several other responses on trim failure while I wrote this, the above is one (of several) possible scenarios.

[Loose rivets]

Water pilot:
This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate.

I still don't understand that 'noise' where there should be steady nose-up trim. Shaking stick suggested. Not convinced.


https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/888x334/trim_switch_difficulties_302feb04575dfa29df951ee7271bea5b90c f0edc.jpg

[RatherBeFlying]

I am wondering how much negative g was produced in the cockpit with the final two MCAS excursions past Vmo. I remember being a front seat passenger when our car rear-ended another car. My legs flew up even though I was strapped in and braced. The driver wasn't and fractured a foot. The accident crews were not military pilots experienced with serious g.

Should we not have a careful look at the stick shaker NNC, given that a failed AoA is setting up the crew for the MCAS knock out combo punch?

I like that at least one pilot suggests pulling the stick shaker breaker once a safe flight path is established.

If failed AoA on one side, is there a way to switch SMYDs - and then perhaps see if the other AoA is correct (sure would like to see three)?

And how about an NNC item to keep flaps down unless switched to a good AOA - that or cut out the automatic trim first?

I am well experienced with non air carrier aviation organisations that sometimes set up pilots to kill themselves (all with the best intentions) and have witnessed a fatality, injury, hull losses, serious incidents and narrow escapes.

A certain paranoia is beneficial, including towards your own attitude.

​​​​In the kingdom of SOPs and multiple checklists, we and management (operator and manufacturer) tend to believe the cotton wool it envelopes us in will protect against all ills we have foreseen.

Works pretty good until something unforseen pops up when the crew better have 737driver's mantra in their back pocket - unless you're in a glider.

[formulaben]

This statement is exactly why I feel that we do not have the complete picture yet. When the trace shows that at least two different pilots did something completely counterintuitive (a few short bursts on the trim rather than holding it down) when they really, really wanted to make the plane go UP instead of DOWN, I think that there is a factor that we do not know about yet. I can't imagine anybody not continuously holding the "UP" switch when they see ground in the windshield, it is just not the way humans operate. You can see Formula 1 drivers adjusting the steering wheel while their car goes airborne, people try to turn on the lights when the power is out, the helmsman will pull on the throttles as the ship with dead engines inexorably heads to crush the wharf, etc. It defies reason that none of the four pilots held the button down to the last.

I don't know what it could be (can you break the switches by pressing too hard on them?)

I am wondering how much negative g was produced in the cockpit with the final two MCAS excursions past Vmo.

I could be wrong but I thought it was clear that it was a full negative 2 Gs, partially due to the crew losing control of the yokes with the last nose down input. Additionally, to Water pilot's point I think that due to the fact that the aircraft was well past Vmo it would appear that the short bursts of nose up trim resulted in very high momentary positive G forces. I firmly believe the crew stopped trimming nose up due to the momentarily high positive Gs on the aircraft...and 5 seconds later the unthinkable happened. Remember, the power is still set at TO, and is accelerating all this time, especially when pointing downward. A high speed nose-down trim input at Vmo+ can't be pretty...

[Cows getting bigger]

Trim Runaways

It would appear Boeing's stance is that the MCAS events are basically Trim Runaways, something that is trained regularly. So, there's a very simple question here: how many 737 trim runaways have been successfully handled over the decades? If the answer is 'lots' then there's strength to their argument. Conversely, if there have actually been very few trim runaways, two catastrophic, one may wish to question whether the event is routinely manageable despite what happens in the sims.

[Fortissimo]

Interesting and very carefully chosen words in Boeing's statement https://boeing.mediaroom.com/news-releases-statements?item=130426, issued in response to media reports yesterday.

Boeing included the disagree alert as a standard feature on the MAX [...] Boeing did not intentionally or otherwise deactivate the disagree alert on its MAX airplanes. The disagree alert was intended to be a standard, stand-alone feature on MAX airplanes. However, the disagree alert was not operable on all airplanes because the feature was not activated as intended.

It goes on to state that if you did not opt for the AOA display, your disagree alert was "not operable". However, there will be an optional service bulletin to tell you how to make it operable on aircraft already delivered. So that's OK then.

[Less Hair]

If MCAS is both "not needed" and in the future will be de-activated after only one run why not get rid of the whole system and train the pilots how to deal with raw nose up slow flight handling instead?

[Cows getting bigger]

Fortissimo, that is a mind-warping read. It reminds me of a scene from Yes Minister!

[groundbum]

Fortissimo, that is a mind-warping read. It reminds me of a scene from Yes Minister!

Boeing know full well the future of the company is on the line here, and one mis-spoken phrase could be the nail in the coffin. This is a can of worms with more to come, that's why B is scared.

[skwdenyer]

Interesting and very carefully chosen words in Boeing's statement...



It goes on to state that if you did not opt for the AOA display, your disagree alert was "not operable". However, there will be an optional service bulletin to tell you how to make it operable on aircraft already delivered. So that's OK then.
How does that square with the previously-stated position that the AOA disagree was an extra cost option?

[Bend alot]

Almost 5000 posts later it is clear it doesn't matter what professional 737 pilots will say about this issue. You guys have made up your mind and no facts will get in the way of that opinion. Nonetheless I will give it another try even though what I am about to write has probably already been mentioned several times:

The MCAS system obviously should have been designed better but the press makes it seem as if Boeing knew the system created great risks but they went ahead with it anyway in order to make more profit. That thought in itself is so absurd that arguing with anyone who believes it, is basically pointless. If Boeing had thought these accidents were likely to occur they would have designed the system differently.

What does this MCAS monster as you call it actually do? It lowers the nose of the aircraft by changing the position of the horizontal stabilizer. It doesn't make the wings fall off, it doesn't set the plane on fire... it only moves the horizontal stabilizer. There is a switch on the pilots control column which moves the horizontal stabilizer and it overrides MCAS each time. I know you guys do not want to face it, but it really is that simple. Now if someone is reading this, thinking if it was that simple why didn't the pilots just do it? First of all they did. The Lion Air Captain did it at least twenty times. And the Ethiopian Captain did trim out the MCAS induced movement completely the second time it activated. So we could already talk a lot about why they didn't do it the whole time, then lower the flaps for landing (MCAS deactivates) and land. Aside from the fact that they did use the trim switch a little bit at least. please have a look at Asiana flight 214, Emirates 521, or Turkish 1951. These are only a few examples of flights were pilots failed to do the most basic thing: flying the aircraft. There were other causes as well and in the case of Turkish and Asiana the flights were not stabilized at 1000 Feet which means they should have carried out a go around preventing both accidents even before the mistake of not flying the aircraft (speed control) was made.


What these accidents show you is that pilots will crash aircraft even though it would have been very easy not to. In the case of Asiana and Emirates there were not even any system failures. Why these things happen is a completely different issue and the answers are to be found in the human factors involved when people fly aircraft. The Fact is, planes crash because pilots do not carry out the basic steps involved in flying an aircraft.

Now one important point I would like to make to all the posters with their Skygod and hindsight comments: First of all, it isn't about blaming the pilots. It is about stating facts. If I or others state that the crew did not carry out the unreliable airspeed memory items when in fact Boeing requires a crew to so in the situation they were in, then that is stating a fact and has nothing to do with hindsight or blame. Stick shaker only on one side, several caution lights going on, differing airspeed indications create a very confusing situation. For exactly that reason there are memory items in order to deal with that situation and they must be carried out. This procedure is a life saver because in that situation it is nearly impossible to figure out which system is malfunctioning and what is actually going on. For that reason: AP off, AT off, FD both off, flaps extended 10° pitch 80% N1. This will set the airplane on a safe flight path and you will continue to climb away from the ground. Now you have time to figure out the problem. This is what we are trained for. This is our job. Carrying out these procedures in that situation has nothing to do with being a skygod and pointing out that the crew did not do it doesn't make us armchair pilots with hindsight. If there is an engine fire on take off I carry out my memory items, if there is a rapid depressurization I carry out my memory items. Again this is what we are trained for.

If the crew had done this on any of these flights we wouldn't even be talking about MCAS. I am not blaming the crew when I say they did no do this. The crew is always just a product of the training department and the general procedures of the airline they fly for. For example, in the case of the Emirates crash, the crew wanted to fly a go around. They only pushed the take off/go around button but did not actually move the thrust lever forward in order to increase thrust on the engines. These pilots were not idiots. I can completely understand how this could happen. Normally as long as the automatic thrust control is engaged, pushing the TOGA button will increase thrust. However, shortly after touch down the automatic thrust control is automatically disengaged. Emirates is an airline with procedures that will not allow pilots to fly manually with the flight directors off for example. I can understand how a crew that is trained to rely on automation will not think to actually move the thrust levers and will not check if the thrust is increasing, despite procedures to do so. Basic skills are lost if one does not use them regularly.

The 737 MAX is grounded and will continue to be grounded for a long time because people think the airplane is unsafe. Furthermore the press reported the Ethiopian pilots carried out all the required procedures and yet they crashed. Why are people like me writing on this forum? It simply isn't true that the 737 MAX is inherently unsafe even with the "old" MCAS and it isn't true that the crew carried out the required procedures. That is not my opinion. That is a fact (again why they did not do it is another issue). If the established procedures had been carried out the planes would not have crashed. There was not one procedure done wrong but several done wrong. Each one of these procedures would have saved the aircraft. Carrying out the unreliable airspeed memory items is one procedure. If the pilots do not do this they are already entering an area where they are not flying the airplane according to procedure anymore but even in that case, carrying out the stab trim runaway memory items correctly once MCAS engaged (please stop these ridiculous comments that the MCAS activation cannot be recognized as a stab trim runaway) would also have saved the plane. If the pilots decide for whatever reason to not even do that, they still have the option of just trimming out the control forces each time MCAS activates (basic flying skills). Again when I am stating what they should have done according to procedure I am not blaming the pilots but only stating the facts of what Boeing says pilots must do in these situations and what we are trained for in our manuals and in the simulator. These recommended procedures would have saved the plane and please realize that there was a flight that had exactly the same problems and they did land safely (and they did not carry out unreliable airspeed mem items and also did not accurately carry out the stab trim mem items and still they saved the plane proving there are several options and it is not a react quickly or die situation).

Final comment: In my opinion crews that are not trained well and are lacking basic skills of flying the aircraft due to company policies are a far greater threat to aviation safety than any system design. I believe we still have a long way to go until we will design systems that never fail (if ever). So it will continue to be up to the pilots to save the day when systems malfunction. There needs to be a focus on enabling pilots to do so a lot more than focusing on how MCAS can be improved.


After what 5000 posts - can you answer why :- At 05:42:54 - Both pilots call out "left alpha vane"

This is 4 minutes and 12 seconds after WOW (take off) and they did not have the AoA disagree option I believe - pretty strange for a reasonable time Captain and low total time cadet to have a "snap" on exact words at that stage of flight.

[Loose rivets]

'Damaged wiring' ( quote from somewhere) and a CB popping out?

If the CB was labelled 'Left Alpha Vane', that would clinch it, I'd guess.

[Escape Velocity]

After what 5000 posts - can you answer why :- At 05:42:54 - Both pilots call out "left alpha vane"

This is 4 minutes and 12 seconds after WOW (take off) and they did not have the AoA disagree option I believe - pretty strange for a reasonable time Captain and low total time cadet to have a "snap" on exact words at that stage of flight.

The Alpha Vane warning light is part of the anti-ice system. It illuminates if the AOA heat malfunctions. It has no bearing on an actual AOA signal failure, only a failure of the vane heating system.

[meleagertoo]

Why don't they just admit it and get on with fixing their problems?!

That is a very good question indeed.


With respect, it's not. Its a very naiive question.

First of all they very clearly are 'getting on with fixing their problems'. What on earth would make anyone dream otherewise?

But more to the point, everything Boeing says and everything they do is governed by lawyers. Every word they utter in public is scrutinised by lawyers before it is spoken or printed. Every action or modification or design approval is swarmend over by lawyers because of the insane levels of liability involved.

A moment's thought would tell you that Boeing cannot admit fault even if it wanted to, because that would render them exposed to unlimited liability. They know they are in for reparations of epic proportions but they must try to limit them out of simple fiancial survival.

In the past Boeing have, I'm told, not changed ambiguous or unclear wording in manuals because doing so would be a legal admission of fault in the original wording, and render them liable post-correction had anyone ever been damaged by the original! That is the sort of legal idiocy Boeing are up against, and I daresay they'd love to be more open - as any decent person would - were they able to. The point is they simply cannot be as open as some would wish, and though their reticence may not be entirely down to this aspect I have no doubt that a great part of it is which leads to statements that appear mealy-mouthed. You have the shysters - and a grossly overdeveloped liability-obsessed legal system - to thank for that.

[meleagertoo]

The Alpha Vane warning light is part of the anti-ice system. It illuminates if the AOA heat malfunctions. It has no bearing on an actual AOA signal failure, only a failure of the vane heating system.

This sort of thing could be significant. If the Alpha vane had been knocked off in a birdstrike I wonder how long it takes to trigger an overheat if there is no vane left to dissipate it? You can bet someone has found out, and if that figure is close to 4min 12 sec it's an indication that might point to the alpha vane physical loss theorey.

[PEI_3721]

Why don't they just admit it and get on with fixing their problems.
Perhaps Boeing does not know which particular aspect fix. The proposals so far limit the effects of an errant AoA value on trim (MCAS issue), but without specifically identifying the source of error: - ‘well whatever it is, the output is limited’.
But the other systems which use AoA appear not to be protected.
How can you prove (certification) that a system is now reliable if the orrigionating source of the problem is unknow, unreplicatable.
https://www.pprune.org/10458103-post806.html

[MurphyWasRight]

This sort of thing could be significant. If the Alpha vane had been knocked off in a birdstrike I wonder how long it takes to trigger an overheat if there is no vane left to dissipate it? You can bet someone has found out, and if that figure is close to 4min 12 sec it's an indication that might point to the alpha vane physical loss theorey.

This was discussed at length somewhere around post 4000 (3000?), a lot of details can be lost in a massive thread, a brief recollection:
The DFR shows initial AoA fault occurs at 5:38:45 followed shortly after by "Primary AOA Heat L" going to off.
Quotes are from the prelim report:

At 05:38:46 and about 200 ft radio altitude, the Master Caution parameter changed state. The First Officer called out Master Caution Anti-Ice on CVR. Four seconds later, the recorded Left AOA Heat parameter changed state.


The heater is in the vane so when the vane departs the circuit would open, this would cause the above.

At 05:42:51, the First-Officer mentioned Master Caution Anti-Ice. The Master Caution is recorded on DFDR.
At 05:42:54, both pilots called out “left alpha vane”.


I don't know the system but assume there was a display of Anti ice caution cause.
This was the second master caution, I will leave it to those with more knowledge whether this was a simple repeat of the first (unacknowledged?) or was re-triggered by other events. Totally reasonable for the crew to not prioritize an anti ice caution at takeoff given the conditions, this would only matter at high altitudes.

The other evidence that strongly supports vane departure theory is the last part of the DFR plot where the left AoA sensor can be seen closely following G forces, caused by the internal (vane) counterweight acting as a pendulum.

[737 Driver]

With respect, it's not. Its a very naiive question.

First of all they very clearly are 'getting on with fixing their problems'. What on earth would make anyone dream otherewise?



Okay, perhaps my comment was a bit too subtle, because it really wasn't directed at Boeing.

Previously, I listed five broad causal links involving different groups:

1. Boeing
2. FAA and other certificate authorities
3. Maintenance/logistical chain (both the airline and possible third-party repair facility involved with Lion Air faulty AOA vane)
4. Airlines
5. Flight crew members

Let me restate my question differently, perhaps a bit more diplomatically.

Why don't each of these groups simply admit they had a role in these accidents and focus on addressing those issues?

I think that we all know that for legal reasons, anyone in the first four groups is going to be very reticent to say anything publicly that will increase their liability exposure. And to be fair, each of these groups is very likely working in the background to correct their lapses. One concern, of course, is that some of these players may not go far enough because they are concerned that comprehensive remedial action will be tantamount to an admission of guilt (i.e. the initial Boeing response to the Lion Air crash).

What about that fifth group? I'm not talking about the crew members who perished. I'm talking about the rest of the professional pilot corps who has just been handed a great, big warning sign that things may not be well in our collective house. I don't think anyone is going to try to sue anyone here, so we really don't have the same excuse as the others.

Yes, it get the the natural human tendency to defend one of our own. We really don't like contemplating that one of our brethren may have had anything to do with the deaths of hundreds of people. "There but for the grace of God," and so forth. All perfectly understandable sentiments, and all significant obstacles to making any changes to the way we do business.

You can't fix a problem until you recognize a problem exists. I humbly suggest that we collectively recognize the crew competency issues within our own ranks and devote our brain cells to addressing that problem rather than lobbing largely ineffectual grenades over the fence.

[737 Driver]

.
Shortly after takeoff, the data suggest that the Left AOA vane was damaged by some foreign object, likely a bird strike. This then likely caused a short in the heating element. This would have annunciated the Master Caution/Anti-Ice lights on the forward glareshield.
.
.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/696x292/six_pack_910bc66833f0356b3f8b114a6177a0fdbfe1f675.jpeg

.
The Anti-Ice annunciation would have directed the pilots to the relevant area of the overhead panel which would have shown a "L Alpha Vane" light illuminated on the Probe Heat control panel.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/452x233/alpha_vane_582b7079313f944b55d10e62decdae6da2d64e1c.jpeg

So when both pilots say "Left Alpha Vane", what is going on is the very standard procedure of verbally announcing the particular annunciator that generated the Master Caution light in the first place. Not really a great mystery.
.

[alf5071h]

Unfotunately most people these days want a quick easy solution to life’s complex problems.
You can see it in politics and in daily life. It leads to repetitive emphasising of dogma and it led to Trump.
You can see it in these discussions.
The tragedy is that some of the items of dogma could be valid, if discussed reasonably but can’t be heard in the torrent.
https://www.pprune.org/showpost.php?p=10459052&postcount=4618

bill,
I agree with the above as a wider ranging overview. This is also reflected in reduced levels of experience and views of ‘Expertise’ *.
A wider concern is where these aspects apply to manufacturing design teams and regulators. These people, like pilots, are Children of The New Age’, many not even born before the 737 first flew.
With respect to older designs, is there sufficient expertise, experience in the skills for revising designs and checking levels of safety to justify retention of ‘grandfather rights’ aircraft.

* https://www.foreignaffairs.com/articles/united-states/2017-02-13/how-america-lost-faith-expertise

[Cows getting bigger]

These people, like pilots, are Children of The New Age’, many not even born before the 737 first flew.




The 737 first flew 9 days after I was born so, at 52 years old, I'm rather pleased I fall on the right side of the line. However, my wife would probably agree with your 'children' sentiment. :}

[alf5071h]

737 Driver, #4683
‘You can't fix a problem until you recognize a problem exists. I humbly suggest that we collectively recognize the crew competency issues within our own ranks and devote our brain cells to addressing that problem rather than lobbing largely ineffectual grenades over the fence.’

You can be as humble as you like, but if the problem is within human thought, that there is a limit to human performance, then the competency issue resides with our (your) thoughts - https://www.pprune.org/showpost.php?p=10459004&postcount=4599

Hopefully you accept that there is a limit; then how is this defined, by whom. Can you enlighten us, where is the evidence of crew competency problems, particularly relating to these accidents.
Or do you use outcome - an accident, to judge competency after the fact.

How might we judge the competency of designers, regulators. With hindsight all appear deficient, but in reality everyone working as best they could, in the conditions they faced; how might they describe their conditions of work and change them.

What the industry requires is the wisdom to foresee how crews will react in extreme, rare, surprising, and life threading situations; without such vision, then crews require help in avoiding these extremes, avoid the situation, change the overall operating environment - change the aircraft system.

Heed the words of James Reason; “it’s very difficult to change the human condition, but you can change the conditions of work”.

[737 Driver]

.
Can you enlighten us, where is the evidence of crew competency problems, particularly relating to these accidents.


I am just going to accept at face value that you haven't read my previous posts. Both I and other participants have commented on this extensively, perhaps too extensively for some people's tastes. Perhaps you should take a moment and review those posts?

[Water pilot]

Interesting and very carefully chosen words in Boeing's statement https://boeing.mediaroom.com/news-releases-statements?item=130426, issued in response to media reports yesterday.



It goes on to state that if you did not opt for the AOA display, your disagree alert was "not operable". However, there will be an optional service bulletin to tell you how to make it operable on aircraft already delivered. So that's OK then.

Isn't it amazing how Boeing's engineering is never wrong, it is just that the customers do not understand it. I should look up and see if some of my old management colleagues work there, this BS is so familiar (although we did it better.)

[slacktide]

Isn't it amazing how Boeing's engineering is never wrong, it is just that the customers do not understand it. I should look up and see if some of my old management colleagues work there, this BS is so familiar (although we did it better.)

How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.

[yanrair]

The 737 first flew 9 days after I was born so, at 52 years old, I'm rather pleased I fall on the right side of the line. However, my wife would probably agree with your 'children' sentiment. :}

Sometimes here we forget that the 737 basic design is actually 1950s since it’s a 707 with two engines missing. When I transferred from 707 to 737 you could nearly have done a differences course! Ok no flight engineer but systems almost the same including the STAB TRIM which is unchanged in basic concept for 60+
now. The 707 had no hydraulic controls except rudder boost and even that was not needed. We had no proper simulator so a lot of training was done on a real plane including stab runaway/ emergency descent from high level and engine failures.
So, when the Max returns to the skies and
ends up with a life of several decades, it will be a century old design with a few electronic add ons when it finally retires.
Y

[MurphyWasRight]

How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.
Agreed that they dont blame the customer in this one, but they seem to just not be able to help themselves when it comes to trying to have it both ways, my bold in quote from release.

Boeing included the disagree alert as a standard feature on the MAX, although this alert has not been considered a safety feature on airplanes and is not necessary for the safe operation of the airplane. Boeing did not intentionally or otherwise deactivate the disagree alert on its MAX airplanes.

The disagree alert was intended to be a standard, stand-alone feature on MAX airplanes. However, the disagree alert was not operable on all airplanes because the feature was not activated as intended.

Reminds me of the classic "a mistake was made" in place of "i made a mistake".
As to safety it would have helped prevent Lion air since it would have flagged AoA on penultimate flight.

[rodlittle]

Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.

[bill fly]

Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.

Rod,
There are about four of us on this thread who think that. So you are in good company.
Boeing has a history of faffing with stab trim to compensate feel inputs and to them I guess it came naturally.
However, a fail mode in the control feel or a separate dedicated feel box would only cause a harder pull - once - and could be trimmed out.
That is what should have been installed (says I) and even if retrofitted may well be:
- cheaper than losing public trust
- easier to explain to the world and the pilots
- a much less critical system than MCAS can become.
B

[GlobalNav]

How did you arrive at that interpretation of the press release? Because I arrived at the exact opposite conclusion. Boeing has admitted that they screwed up by tying the activation of the AOA Disagree alert to the the selection of the AOA indicator customer option.

I don't see any language in the release that insinuates that this was in any way the customer's fault or that it is to a lack of the customer's understanding.

Regardless of the presence of a AOA disagree alert, the system had the data with which to disarm MCAS. Boeing’s recent statements that nothing was wrong with the design has already twice been disproven. And it’s wrong for at least two reasons, use of a single AOA sensor, the second, that when AOA sensors disagree, the MCAS is not disarmed.

[Thrust Augmentation]

There are about four of us on this thread who think that.

Count me in on that!

Nothing that some year dot bicycle technology (much like the rest of the flight control system) couldn't have resolved with simplicity, redundancy & no additional training requirements - it's considering this that make me wonder far more broadly about MCAS.

[FrequentSLF]

Regardless of the presence of a AOA disagree alert, the system had the data with which to disarm MCAS. Boeing’s recent statements that nothing was wrong with the design has already twice been disproven. And it’s wrong for at least two reasons, use of a single AOA sensor, the second, that when AOA sensors disagree, the MCAS is not disarmed.
The wiring diagram of the MCAS/STS is very eloquent. The pilots have no way to disarm the MCAS/STS. Is either both ON or CUT OFF, which means also thumb switches are disabled if in CUT OFF position. NG wiring diagram shows that STS could have been disarmed by one of the switches, keeping operative the thumb switches.

[infrequentflyer789]

Dare I say it, but the differences between A & B philosophy really show here. In the early days of A, I was like many pilots - dubious and wary of automation. Over a generation of flying later we seem to have got our head around they fact that HAL(A) has matured, is now rather good at his job and, generally speaking, our side of the house only gets into trouble when we ignore HAL(A). Meanwhile, HAL(B) appears to still be at school and capable of having hissy-fits, just like my teenage daughter. :)


I think that is unfair to Boeing - B has had a proper grown up HAL since 777 and many think it is superior to the A model (certainly it came after and learned from it). From an engineering point of view (I accept that pilots may have a preference) there isn't much to choose between C* and C*U, sidesticks or yokes - both systems work and are well proven now.

What was clear to this engineer was the difference in philosophy between A & B Hals - HAL(A) will protect the pilot from him/herself overriding control inputs because HAL(A) knows best, while HAL(B) will warn pilots and make difficult what it considers as "incorrect" control inputs it will always allow the pilot to stuff it up if they really want because the pilot knows best.

The hissy-fit system HAL(MAX) seems to me to overturn the old B philosophy and head much more towards A, but worse, it decides it knows best (where best is mistrim AND to the stops at high speed and low alt) based on a single AOA sensor rather than the multiply redundant sensor sets of HAL(A) (or B).

That to me is the really sad thing - Boeing knows (or knew) how to do this stuff properly, but for some reason they decided not to for MAX. It's not just doing FBW properly 777-style, it's MCAS itself - it's looking like they ripped MCAS straight off the KC-46, except that there it uses 2 AOA inputs, so at some point in copying the system they reduced the number of AOA inputs to the MCAS system. Why on earth would anyone do that?

[737 Driver]

No, just show us the evidence.

Please define what you mean by "evidence."

BTW, does that definition also apply to all the other players in the chain of causation, or just the aircrew?

[gums]

Salute!
From Bill
If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT........
=======
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift

The problem, Bill, et al, is that the plane required an aerodynamic fix for pitch moments approaching the stall AoA. Sure, in noirmal, non-FBW systems you would expect increasing back force to increase AoA. The new motor mount and such resulted in less back force per each increase in AoA - aero force, not the artificial feel sustem they already had. A pure cable system with no "help" would have made that very obvious for most of us here, especially those with lottsa light plane time. So Boeing figured they would just crank the stab to generate more nose down pitch moment, and the existing feel and such would take care of everything else, huh?
.
- Make the sucker nose heavy and use a single AoA vane to trigger it. Don't sweat a FUBAR vane, as the stick shaker would prolly be going off and provide a clue that something wasn't right
- Let her rip for almost ten seconds and 2.x units nose down, then wait 5 seconds and do it again.
- Don't look at airspeed, just flaps and autopilot settings besides the AoA vane
- To disable the doofer, simply turn off all the electric trim to the stab. Neat, huh? Oh, you lose the yoke trim Gums! No biggie, we can crank that little wheel 50 times. Just don't get fast.
- Yeah that's it. And let's increase the authority of MCAS a bit to be on the "safe" side and don't advertise this, as it might require a sim ride or something.
================
And finally today's comment: @ driver. The first crew call I can see about AoA vane is about 4 minutes from WoW. It could be that at that point they turned the electric trim back on.. at 43:11 we see manual trim from yoke, and sure enuf, 5 seconds later we see MCAS crank the trim down to 1.0 from 2.3 units and they were doomed.

Gums sends...

[Cows getting bigger]

Far more eloquently presented than my effort. I wholeheartedly agree.

[MurphyWasRight]

Originally Posted by weemonkey https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-233.html#post10460010)
No, just show us the evidence.
Please define what you mean by "evidence."

Please define what you mean by "evidence."

BTW, does that definition also apply to all the other players in the chain of causation, or just the aircrew?

At this point (for either accident) "evidence" in a formal sense is not available to the general public.

What is available are a precious few facts and (sometimes strongly held) opinions and theories based on individuals backgrounds.

While some (my self included) may disagree with 737 drivers analysis on some points he has presented detailed explanations and insight that clearly provide an experienced pilots view of things.

In that context it would be equally (not) usefull to say "show me the evidence it was -not- primarily pilot error".

If you have not read his longer posts they are well worth reading, even if you do not end up agreeing with all the points.





https://www.pprune.org/images/statusicon/user_online.gif https://www.pprune.org/images/buttons/report.gif (https://www.pprune.org/report.php?p=10460030)

[737 Driver]

And finally today's comment: @ driver. The first crew call I can see about AoA vane is about 4 minutes from WoW.

Gums sends...

From the preliminary accident report:At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in 3⁄4 seconds while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained active until near the end of the recording. Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side values until near the end of the recording.

At 05:38:43 and about 50 ft radio altitude, the flight director roll mode changed to LNAV.

At 05:38:46 and about 200 ft radio altitude, the Master Caution parameter changed state. The First Officer called out Master Caution Anti-Ice on CVR. Four seconds later, the recorded Left AOA Heat parameter changed state.

<snip>

At 05:42:51, the First-Officer mentioned Master Caution Anti-Ice. The Master Caution is recorded on DFDR.

At 05:42:54, both pilots called out “left alpha vane”.


​​​​​​
From the data provided, it appears that the Left Alpha Vane warning was triggered within 10 seconds after liftoff. The First Officer called out "Master Caution, Anti-Ice" as would have been procedure. Normally, that call should have been followed up with a verbalization of what particular malfunction triggered the Master Caution light. The crew did not actually get around to doing this until a little more than four minutes after the light first illuminated.

Further examination of the DFDR output indicates that the first Master Caution alert was reset. This is normal procedure to allow for additional alerts, but it also extinguished the "Anti-Ice" annunciator. It appears that the crew simply forgot to look for the actual malfunction annunciated on the overhead panel. For reasons, that are not entirely clear from the data, the Master Caution light came on again at around the 5:42:50 mark, re-illuminating the "Anti-Ice" annunciator. The Master Caution light was reset again. It is at this point, four minutes after the original alert, that the pilots looked up and confirmed the "L ALPHA VANE" annunciation.

737 Driver sends.....

[Avionista]

737Driver and his cohorts seem intent on diverting attention towards alleged deficiencies in the airmanship of the crews of the two 737 max aircaft that crashed rather than dealing with the real villains of the piece, namely, the FAA and Boeing. I hope that EASA and other foreign regulators hold the FAA's and Boeing's feet to the fire and refuse to lift their grounding of the MAX until a proper SAFE fix has been implemented.

MCAS needs to be removed completely from the 737 Max as it is a far too powerful and dangerous solution to the issue of stick force gradient at high angles of attack. EASA et al should demand that a stick-pusher system should be provided to meet the certification requirements, or else the MAX will not fly passengers in Europe.

Personally, I hold the FAA most culpable for the crashes that have occurred due to MCAS. Whilst aircraft manufacturers such as Boeing, or Airbus, may be tempted to cut corners in pursuit of profit, the regulators are supposed to prevent unsafe commercial aircraft from receiving certification.

[ams6110]

Does anyone on this topic know about Boeings system design ? and if so can they please explain to this simple pilot why mcas was designed in the waay it was, If I understand correctly MCAS is a sub-system designsd solely to counteract the lift generated by the engine nacelles at higher than normal AOT. It does this by trimming the stab nose down meaning that if the MCAS system fails due to incorrect AOA info, unless corrected by the PF its heading for disaster.
Why did they not simply alter the elevator feel circuit so that higher force was required to pull back on the stick, sorry column if the AOT was too high and the stick forces were reducing due to the nacelle lift
This could surely have been done so that forward ie nose down column movement was not affected.
This would mean that what ever happened the aircraft would not be left with a nose down trim and would not therefore be trying to fly into the ground.

This was discussed somewhere in the thousands of preceding posts. I think we've reached the point (probably long past it really) where there's nothing more to really be said until new information is released from the investigating authorities.

Basically (if I recall correctly) the elevator feel doesn't operate in a continuously variable fashion relative to AoA. Also the elevator feel system does not have enough authority to maintain the linear stick force called for by certification reqirements. Finally, EFS operates during the stall, stick shaker active, etc. while MCAS (or its effect on stick feel) is needed prior to the stall.

[alexandersparry]

Speaking for me and just about all of my colleagues of a quite big IT company having its main location in germany: I'll never ever fly a boeing again unless the 737 MAX Issue is resolved including a full analysis *what* went wrong certifying this aircraft.

From an engineers point of view it is quite incredible what has happened in this specific case. May the pilots have partial guilt or not, at least the following facts remain:
* no redundancy for a safety-critical subsystems' sensor
* no sanity-check of input-values of a safety-critical subsystem (e.g. not checking differential of movement, not checking absolute values, not comparing against other available sensors, not checking against absolute - i.e. measureable - orientation against groun(
* no coaching of pilots
* cross-linking of MCAS with assisted trim

In our company boeing is being called as "Boing", which in german means "Crash!". Anyone having to fly who determines to have been booked on a boing 737-MAX (i.e. crash 737-MAX) may refuse to fly, requiring the company to re-book. Do you even grasp what this means?

The longer boeing refuses to admit the obvious, glaring deficits in the MCAS implementation the longer it will permanently lose trust. Whatever 737driver or anyone else says will not rectify this, quite the opposite. Even if it is true to a certain degree.

[gums]

Salute!

Excuse me, Driver, but your post about all the warning lights you say in last sentence the crew called out “left vane”. And I do not see this right after WoW for several minutes. Sure, many alarms and such went off right away, and looks to me that somewhere along the way they turned off the electric trim. Can post timeline later.
EDIT WITH COCKPIT STUFF:
Takeoff at 5: 38 +/1 a second or two
At 05:39:45, Captain requested flaps up and First-Officer acknowledged. One second later, flap handle moved from 5 to 0 degrees and flaps retraction began.
[that is almost two minutes after WoW)

At 05:39:50, the selected heading started to change from 072 to 197 degrees and at the same time the Captain asked the First-Officer to request to maintain runway heading.
[no discussion of AoA vanes yet almost two minutes after WoW]

At 05:39:55, Autopilot disengaged,

At 05:39:57, the Captain advised again the First-Officer to request to maintain runway heading and that they are having flight control problems.

At 05:40:00 shortly after the autopilot disengaged, the FDR recorded an automatic aircraft nose down (AND) activated for 9.0 seconds and pitch trim moved from 4.60 to 2.1 units. The climb was arrested and the aircraft descended slightly.
[The MCAS activates and the real circus begins]

Gums....

[MurphyWasRight]

Salute!

Excuse me, Driver, but your post about all the warning lights you say in last sentence the crew called out “left vane”. And I do not see this right after WoW for several minutes. Sure, many alarms and such went off right away, and looks to me that somewhere along the way they turned off the electric trim. Can post timeline later.

Gums....

They had 2 master 'anti ice' cautions, the crew only announced cause after second one, not surprising since they had a lot going on and anti ice would not be of much concern given the conditions until they reached altitude.

My post below has a timeline for when they turned off electric trim including quotes from prelim report.

https://www.pprune.org/showthread.php?p=10459320

[gums]

Salute1

Thanks, Murph

My point is that they did not call out AoA vane for 3 or more minutes, even tho they had the ice light and so forth.

Gums sends....

[ph-sbe]

Speaking for me and just about all of my colleagues of a quite big IT company having its main location in germany: I'll never ever fly a boeing again unless the 737 MAX Issue is resolved including a full analysis *what* went wrong certifying this aircraft.


Oh man, here goes the Boeing stock. Oh wait, they don't care.

Boeing sells aircraft to airlines. Yes, in this particular case, it seems that something went wrong that should not have gone wrong. It will be fixed, and the company will bleed a lot of cash for it.

I could also announce that I will never buy a Volkswagen again because of the diesel scandal. However, the same thing applies: something went wrong that should not have gone wrong. It will be fixed, and the company will bleed a lot of cash for it.

In fact, when this is fixed, I'll be more than happy to fly the MAX because I'm pretty sure that with all that media attention if anything is going to be fixed properly, it will be MCAS. With a blank check from Boeing's beancounters.

[Organfreak]

737Driver and his cohorts seem intent on diverting attention towards alleged deficiencies in the airmanship of the crews of the two 737 max aircaft that crashed rather than dealing with the real villains of the piece, namely, the FAA and Boeing.

This is unfair, bordering on the slanderous. Are 737 pilots who happen to agree with him about airmanship really his "cohorts"? You make it sound like a plot.
Mr. Driver has, time and again, acknowledged the glaring "other factors" and has bent over backwards to be fair.

Speaking as an informed passenger, try to see my POV: If there is something wrong with the airplane you're riding, wouldn't you want the very best piloting skills possible sitting up there in the pointy end??? I sure would! I am shocked that there's so much sentiment against "Just fly the damned plane!"

[ktcanuck]

Stick force reduces as AoA increases under particular flight conditions on, and only on, the 737 MAX. This is not certifiable under FAA rules.

I don't know who originally stated the first part to be the case but it is apparently at the foundation of all that we have talked about and whose chosen "correction" is in whole or in part the cause of the loss of almost 400 lives.

What mentality uses uncommanded movement of the horizontal stab (MCAS) to correct for a decrease in stick force?

Perhaps a mentality that knows that if the 737 MAX were to actually stall under those particular conditions it would be game over?

[737 Driver]

My point is that they did not call out AoA vane for 3 or more minutes, even tho they had the ice light and so forth.

Gums sends....

I don’t think anyone is disagreeing with your observation, and Murph and I attempted to offer an explanation as to why this may have happened. The crew was task saturated, so they didn’t verbalize this annunciation earlier. It doesn’t really seem to have anything to do with any action they did or did not take. Am I missing something here that you are trying to say?

Driver sends.....

[Loose rivets]

Avionista #4661

MCAS needs to be removed completely from the 737 Max as it is a far too powerful and dangerous solution to the issue of stick force gradient at high angles of attack.

We know why it's there, and more or less what it does, but I have to agree with this part of the above post. It's been nagging at me since November.

Why is such a powerful tool used to simply stop the PF heaving back too easily at a high AoA?
Boeing chose not to use conventional stall protection but instead devise a system that changes the aircraft's overall handling at a critical time. For a few moments, they are trying to make the MAX be something it's not. The necessary certifiable handling characteristics are synthesised by moving over 47 feet of flying surface - it's as though the design of the entire aircraft was being momentarily tweaked to cover one issue.

This vast surface is altered to give this synthetic nose down just at a time there's presumably a danger of the wings stalling. If it was capable of a lightning fast return to normal datums, it would just about be acceptable, but any return has to be done by the cranking of that jack. On that dark and stormy night, a last minute change of runway and a moment's inattention. Is that extra weight on the pole going to save the day? If it doesn't, even with a fully serviceable aircraft, it seems to me that the problem of an embarrassing stick shake could be turned into something orders of magnitude worse.

[568]

I don’t think anyone is disagreeing with your observation, and Murph and I attempted to offer an explanation as to why this may have happened. The crew was task saturated, so they didn’t verbalize this annunciation earlier. It doesn’t really seem to have anything to do with any action they did or did not take. Am I missing something here that you are trying to say?

Driver sends.....
Agree with most of your comments relating to this post and others.It would be interesting to see if the crew of Lion Air and ET received any UPRT/UAT training in any previous recurrent training.

[Lost in Saigon]

Avionista #4661


We know why it's there, and more or less what it does, but I have to agree with this part of the above post. It's been nagging at me since November.

Why is such a powerful tool used to simply stop the PF heaving back too easily at a high AoA?
Boeing chose not to use conventional stall protection but instead devise a system that changes the aircraft's overall handling at a critical time. For a few moments, they are trying to make the MAX be something it's not. The necessary certifiable handling characteristics are synthesised by moving over 47 feet of flying surface - it's as though the design of the entire aircraft was being momentarily tweaked to cover one issue.

This vast surface is altered to give this synthetic nose down just at a time there's presumably a danger of the wings stalling. If it was capable of a lightning fast return to normal datums, it would just about be acceptable, but any return has to be done by the cranking of that jack. On that dark and stormy night, a last minute change of runway and a moment's inattention. Is that extra weight on the pole going to save the day? If it doesn't, even with a fully serviceable aircraft, it seems to me that the problem of an embarrassing stick shake could be turned into something orders of magnitude worse.

It has been said time and time again: MCAS is not for stall protection.

MCAS is only there to provide the correct elevator feel at high angles of attack to meet the FAA certification requirements. You can still stall the aircraft, the only difference is how the elevator feels. With MCAS the elevator feels like every other aircraft you have flown. Without MCAS the elevator feels light at high angles of attack.

In my opinion, the original MCAS design was really not that big a deal. Boeing and FAA probably decided one Angle of Attack sensor was enough because it still flies just fine without MCAS. It just feels different. If the Angle of Attack sensor fails and MCAS operates incorrectly, you just trim it away with the thumb switches. (Lowering the flaps for landing also deactivates MCAS) If you get tired of playing with the trim switches to keep the nose up, then just turn off the Electric Stab switches and trim manually. No big deal right?

WRONG.... It seems that there are pilots who will have difficulty with this simple concept of FLY THE AIRCRAFT so now Boeing has refined MCAS to make it less likely to confuse these pilots. Now it takes 2 Angle of Attack sensors to agree before MCAS activates, AND it will not apply nose down trim repeatedly. That should make it safe for all pilots. YES?

But, for some reason, people are still not satisfied. It seems these people have a real hate-on for Boeing and the FAA. I think this is all an over reaction to a simple design underestimation that has an easy solution.

[Water pilot]

It has been said time and time again: MCAS is not for stall protection.

MCAS is only there to provide the correct elevator feel at high angles of attack to meet the FAA certification requirements. You can still stall the aircraft, the only difference is how the elevator feels. With MCAS the elevator feels like every other aircraft you have flown. Without MCAS the elevator feels light at high angles of attack.

In my opinion, the original MCAS design was really not that big a deal. Boeing and FAA probably decided one Angle of Attack sensor was enough because it still flies just fine without MCAS. It just feels different. If the Angle of Attack sensor fails and MCAS operates incorrectly, you just trim it away with the thumb switches. (Lowering the flaps for landing also deactivates MCAS) If you get tired of playing with the trim switches to keep the nose up, then just turn off the Electric Stab switches and trim manually. No big deal right?

WRONG.... It seems that there are pilots who will have difficulty with this simple concept of FLY THE AIRCRAFT so now Boeing has refined MCAS to make it less likely to confuse these pilots. Now it takes 2 Angle of Attack sensors to agree before MCAS activates, AND it will not apply nose down trim repeatedly. That should make it safe for all pilots. YES?

But, for some reason, people are still not satisfied. It seems these people have a real hate-on for Boeing and the FAA. I think this is all an over reaction to a simple design underestimation that has an easy solution.
I read several hundred posts ago MCAS uses a circuit that trims faster than the thumb switches, which is a key part of the problem. Just using the thumb switches is what the first victims did, and we have all been told that was obviously wrong and poor airmanship.

This was not a case of unaware pilots not noticing that the plane was trimming down, or not knowing the basics of how to fly an airplane. The most convincing arguments that I read here for pilot error is that they were too slow to recognize the problem and use the procedure that Boeing specifies (although even that gets fuzzy as Boeing used to specify a more detailed procedure that is now not taught because runaway trim was rare to non-existant before the MAX.)

The variety of "simple concepts" presented as solutions here that would have also crashed the MAX is concerning. My understanding of the current "party line (see Dominic Gates in the Seattle Times) is that the first pilots erred by not turning the electric trim off, and the second pilots erred by turning the electric trim off too soon. My unqualified understanding is that the ideal procedure is to use the electric trim to undo the MCAS input (while not letting go of the switch for a moment) and then (presumably without letting go of the trim button) turning off electric trim to disable MCAS. (I do not believe that is the standard response to a trim runaway which is an argument against the concept that the pilots erred by not applying the trim runaway procedure.)

We cannot forget that two planes from two different respectable airlines with legally qualified pilots crashed in short order, which is not something that happens very often. There is so far no reason to believe that those pilots were any more or less skilled than the thousands of their brethren so if this was just the sad fact that pilots don't know how to fly anymore, we should expect to see major airplane crashes every six months or so. We do not, which is why the plane was grounded despite Boeing's and the FAA's objections.

[Lost in Saigon]

I read several hundred posts ago MCAS uses a circuit that trims faster than the thumb switches, which is a key part of the problem. Just using the thumb switches is what the first victims did, and we have all been told that was obviously wrong and poor airmanship.


My understanding is that ANY use of the thumb switches disables MCAS. Any type of nose up trim stops the MCAS dead in it's tracks. If you release the thumb switch, a faulty "original" MCAS will start trimming again but only after 5 seconds. It should have been easy enough to keep stabbing the the nose up trim as much as you need to overcome the MCAS down trimming. At that point you would have to realize that the trim is not behaving like you want it to, and you should hit the Stab Trim Cut Out switches and just use the manual trim wheel.

Any "poor airmanship" criticism is just because they did not keep on using the thumb switches to keep nose up trim. There may be some underlying issues we don't know about that prevented them from operating the nose up trim. Until we get the full accident report, we don't really know if that is true.

[MemberBerry]

Speaking as an informed passenger, try to see my POV: If there is something wrong with the airplane you're riding, wouldn't you want the very best piloting skills possible sitting up there in the pointy end??? I sure would! I am shocked that there's so much sentiment against "Just fly the damned plane!"

I know what you really mean but, as another informed passenger, if there is actually something wrong with the airplane, the pilots should NOT fly the damned plane. The plane should not leave the ground with passengers on board if the pilots are not confident that the aircraft is safe to fly.

In fact that's what I heard commercial pilots say when asked about the things they do to keep us, the passengers, safe: If they feel that there is anything wrong with the aircraft that could affect the safety of the flight, they will not take off until the issue is taken care of. Period. No ifs and buts.

But in this case, after the Lion Air accident, the pilots trusted Boeing, the FAA and the airlines when they claimed that the MAX is not unsafe, and just continued flying the damned plane. In my opinion that trust has been misplaced.

Anticipating accusations of being hysterical, I feel I need to recap some of the unbelievable things I have read in the last months about how Boeing failed at making safety their primary concern, while the FAA was a watchdog that didn't have teeth sharp enough to prevent it, and also some of the stuff the airlines did that contributed:

- the latest blunder about the AOA disagree warning being disabled "by accident" on the MAX
- recent whistleblower reports about damage to the wiring of the AOA sensors
- the redesign of the cutout switches that prevents disabling automatic trim independently from the manual electric trim
- relying on a single AOA sensor for the MCAS function
- increasing the amount of trim MCAS can apply in one run from 0.6 to 2.5 without re-evaluating its safety
- hiding the existence of the MCAS function and its behavior from the pilots
- a pilot that demanded more training for the MAX being ignored and then punished by his airline when he insisted: https://qz.com/1584233/boeing-737-max-what-happened-when-one-us-pilot-asked-for-more-training/
- a pilot that said he didn't feel prepared and had significant issues on his first flight on the MAX: https://www.theatlantic.com/notes/2019/03/heres-what-was-on-the-record-about-problems-with-the-737-max/584791/
- making the manual trim wheels smaller to fit the larger displays starting with the NG, and also making them harder to use
- Boeing accepting sub-standard hardware components from its suppliers, then literally hammering them in place or drilling additional holes in the components when they didn't fit properly, see "Problems with Boeing 737 next generation with structural dangers reported SBS​ dateline Australia": https://www.youtube.com/watch?v=vWxxtzBTxGU
- foreign objects found on aircraft delivered by Boeing
- airlines refusing to accept aircraft assembled in one of Boeing's factories due to quality issues
- Boeing ignoring employees that reported quality issues in its factories or the factories of their suppliers
- FAA mostly ignoring whistleblowers that did the same.
- Boeing firing the whistleblowers and the people reporting quality issues.
- The battery issues on the Dreamliner (the Al Jazeera investigation): https://www.youtube.com/watch?v=rvkEpstd9os

But with all that going on somehow some people are still extremely surprised about the criticism towards Boeing and the FAA.

The problem goes deep, and just fixing MCAS is not enough. The factors that allowed the issues with MCAS to slip through the cracks, assuming they were not hidden intentionally, also need to be fixed. And based on what I learned so far I think those factors are the under-funding and maybe even corruption within the FAA, and having some unethical people in key positions at Boeing and some of the airlines, that prioritized short term profit over safety.

[DaveReidUK]

I read several hundred posts ago MCAS uses a circuit that trims faster than the thumb switches, which is a key part of the problem. Just using the thumb switches is what the first victims did, and we have all been told that was obviously wrong and poor airmanship.

If you look at the FDR traces, there's not a huge difference between the rate at which the stab moved ANU in response to crew trim commands, and the rate that MCAS drove it AND. Time to knock this one on the head.

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/130x74/ei_pitch_trim_fc02da6a46bf64647da30f9f6b83f2a80fcfb5b1.jpg

[safetypee]

Speaking as an informed passenger, try to see my POV: If there is something wrong with the airplane you're riding, wouldn't you want the very best piloting skills possible sitting up there in the pointy end??? I sure would! I am shocked that there's so much sentiment against "Just fly the damned plane!"
However, if the aircraft’s response to a single failure reduces the ability of any piloting skills to recover the aircraft, then discussing the quality of flying become irrelevant.

The assumed use of electric trim depends on understanding the nature of the failure - no direct warning alert. MCAS trim surpasses elect trim - 10 sec to 5 sec, then there is a point where elect trim becomes ineffective, it should be inhibited before then, there is a (coincident) point where manual wheel trim is ineffective (physically impossible to move), so that the residual control force and / or manoeuvre cannot be flown.

If speed of awareness and trim action are important, then the aircraft systems must support these; you cannot expect to cure a poor design by ‘improving’ every pilot, and expecting that enhanced performance every day in every situation.

Water pilot,
We cannot forget that two planes from two different respectable airlines with legally qualified pilots crashed in short order, which is not something that happens very often. There is so far no reason to believe that those pilots were any more or less skilled than the thousands of their brethren so if this was just the sad fact that pilots don't know how to fly anymore, we should expect to see major airplane crashes every six months or so. We do not, which is why the plane was grounded despite Boeing's and the FAA's objections.
:ok:

[Mac the Knife]

Even Chuck Yeager had to ride the rails a few times....

Mac

[LowObservable]

Much of this discussion continues to obfuscate some fundamental and indisputable points.

In 2019, the loss of two aircraft to the same cause within less than two years of service entry is anomalous.

Whatever one may think about automation and piloting skills, developments in aircraft technology have paralleled not only a continuous improvement in safety, but an improvement that has been worldwide and near-universal. So far, we have not seen any evidence of an actual decline in piloting standards.

This specific failure - which can barely be called a chain - has a kill probability of 0.667. A surface-to-air missile development team would dream of anything like that.

If there were more incidents of AoA-vane failure triggering MCAS, but with the aircraft being recovered, there would be strong grounds for the FTFA-fundies' argument. As it is, their case is purely speculative.

[wiedehopf]

Much of this discussion continues to obfuscate some fundamental and indisputable points.

In 2019, the loss of two aircraft to the same cause within less than two years of service entry is anomalous.

No one is disputing that the current implementation of MCAS was dangerous and led to the 2 accidents.
If those 2 planes could have been saved by better pilot training is very much an orthogonal discussion.


And those fundamental and indisputable points have been discussed over and over, so why do you have a problem with people discussing pilot training?

[meleagertoo]

We cannot forget that two planes from two different respectable airlines with legally qualified pilots crashed in short order, which is not something that happens very often. There is so far no reason to believe that those pilots were any more or less skilled than the thousands of their brethren so if this was just the sad fact that pilots don't know how to fly anymore,
I nearly spat my porridge when I read the first line of that.
Water pilot, do yourself (do us all) a favour and look LionAir up on wiki - and tell me if it's accident and incident record - along litany of written off airframes and fatalities - plus bribery at governmental level and flying routes wholesale without licences constitutes a "respectable" airline in your book. Look at the crew + engineering actions and procedures on the days preceeding their accident too...
Also check Indonesia's national historical accident record, which explains why for so long all its airlines were banned from EU airspace, and how recently they were given a reprieve. Doubtless you'll assert that big cats can change their spots. I don't doubt it. What I do doubt is whether they have done so sufficiently.
Of course their latest accident just might be an extremely unfortunate anomaly that a newly reformed company didn't deserve, but with a statistical background like theirs and the evidence from the preceeding flights not many would be taking bets on that I fear.

I can't comment much on Ethiopian, they do seem to have a good record although that statement is often heard qualified, but the non-stop floods of reports over many years of grossly exceeding pilots' flying hours as a matter of routine, failures to honour contracts or provide pay on occasions plus the latest suggestions about failure to publish/incorporate Boeings safety bulletins and lack of systems awareness even after the Lion Air accident make it plain that parts of their operation at least are not up to the sort of standards we expect in N Europe and the US, but I don't think we can judge their overall training quality and standards from the actions of just two pilots though it must raise doubts.
Do not mistake this for racism as doubtless some with auto-offend enabled will do. It most certainly isn't. It's called being honest and realistic. The only bit that isn't proven to be factual yet is the Ethiopian amendment and awareness states, the rest is all hard fact, and even those doubts seem to be pretty much accepted if unproven as yet.

Both nations have historically beeen known for an almost total lack of democratic process, a history of repressive military rule (aka Dictatorship), a highly developed hierarchical society and steep if not near vertical authority gradients in the cockpit. None of these are condusive to the sort of open reporting culture of operations that so many of us here take for granted and it behoves us to take these cultural differences into consideration when we consider what's happened out there.
I've worked in Africa, including Ethiopia and things are simply not done the way we N Europeans expect out there. It shocks one at first but that's just the way it is, just as the way different nations have different driving habits and styles so they do too in Aviation. They also have different ideas on legal matters, so 'legally qualified' may mean one thng to you and something entirely different in a gynae clinic in a fovella in Rio...

This is just another aspect of what's turning into an extremely complex matter which doubtless will become even more so before any resolution is found.

[GordonR_Cape]

@meleagertoo

No one is disputing that the current implementation of MCAS was dangerous and led to the 2 accidents.
If those 2 planes could have been saved by better pilot training is very much an orthogonal discussion.

And those fundamental and indisputable points have been discussed over and over, so why do you have a problem with people discussing pilot training?

To take a contrarian viewpoint: If an aircraft is not safe to be operated by airlines in countries whose pilots are not top-notch, then it should not be sold to those airlines/countries. Or fix the aircraft, so that it is safe to be operated by less-than-perfect pilots. End of (my version of) the story...

The implication is that training outside the US and other "first world" countries is not up to standard. That may or may not be true, but nobody on this forum has control over all of those countries, and that discussion belongs elsewhere on the forum.

[oggers]

I can't comment much on Ethiopian, they do seem to have a good record although that statement is often heard qualified, but the non-stop floods of reports over many years of grossly exceeding pilots' flying hours as a matter of routine, failures to honour contracts or provide pay on occasions plus the latest suggestions about failure to publish/incorporate Boeings safety bulletins and lack of systems awareness even after the Lion Air accident.....

You can add to that list the findings on the crash of ET409, a totally serviceable 737, into the Med in 2010...."the probable causes of the accident were the flight crew's mismanagement of the aircraft's speed, altitude, headings and attitude through inconsistent flight control inputs resulting in a loss of control and their failure to abide by CRM principles of mutual support and calling deviations."

More significant even than the probable cause is that both Ethiopian Airlines AND their CAA rejected the findings out of hand, Therefore it is reasonable to doubt they have acted to address the signficant shortcomings identified, and all the more reasonable that the performance of the crew of ET302 is discussed.

[bill fly]

From Gums

The problem, Bill, et al, is that the plane required an aerodynamic fix for pitch moments approaching the stall AoA.

Hi Gums,
That's not what I have understood the certification problem to be - which was that stick back force did not increase enough at higher AoA to satisfy the requirements. That is not quite the same as a pitch up problem, although it could lead to one, depending on pilot reaction.
If what I understood back there is true - and it came from a very reliable source quite early on on this thread, there can be a few ways to increase stick back force, without going the aerodynamic route.
To my mind, this is preferable than putting large inputs into the stab and has the added advantage that if a fail input into a direct feel-controlling software or linkeage occurs, it is much easier to manage.
Of course if all works normally, the feeling in the design case (high AoA) for the pilot would be a similar one. Of course Boeing wouldn't deliberately put a time bomb in their system . but as we see, one was waiting there.
Greetings, B

PS The quote you used wasn't from me - although I subscribe to a lot of the sentiment in it.

[MurphyWasRight]

From Gums

The problem, Bill, et al, is that the plane required an aerodynamic fix for pitch moments approaching the stall AoA.

Hi Gums,
That's not what I have understood the certification problem to be - which was that stick back force did not increase enough at higher AoA to satisfy the requirements. That is not quite the same as a pitch up problem, although it could lead to one, depending on pilot reaction.
If what I understood back there is true - and it came from a very reliable source quite early on on this thread, there can be a few ways to increase stick back force, without going the aerodynamic route.
To my mind, this is preferable than putting large inputs into the stab and has the added advantage that if a fail input into a direct feel-controlling software or linkeage occurs, it is much easier to manage.
Of course if all works normally, the feeling in the design case (high AoA) for the pilot would be a similar one. Of course Boeing wouldn't deliberately put a time bomb in their system . but as we see, one was waiting there.
Greetings, B

PS The quote you used wasn't from me - although I subscribe to a lot of the sentiment in it.
It may (or may not) be helpful to remember that the autopilot does not require MCAS help.
This reinforces the fact that this is fundamentally a stick feel issue rather than a critical instability that could kick in under extreme but still in certified envelope conditions.

[meleagertoo]

@meleagertoo



[QUOTE]To take a contrarian viewpoint: If an aircraft is not safe to be operated by airlines in countries whose pilots are not top-notch, then it should not be sold to those airlines/countries. Or fix the aircraft, so that it is safe to be operated by less-than-perfect pilots.

The implication is that training outside the US and other "first world" countries is not up to standard. That may or may not be true, but nobody on this forum has control over all of those countries, and that discussion belongs elsewhere on the forum.
That contrarian viewpoint, if I may say so, is naiive in the extreme. One can no more withold aircraft sales on those grounds than one could of cars or power tools - They claim to be operating to international standards, if they choose to backslide on that why/how is it Boeing's or Washington's job to judge - ? Wouldn't that be a particularly unpleasant form of self-righteous paternalism? (a phrase I never thought I'd actually use myself!) WE allow them into or airports - we can't then refuse to sell them aircraft, or de we prefer our skies filled with their legacy antique vodka burners dthat haven't seen a spanner in a year and with 28 bald tyres out of 28 instead?
No one but you suggeted that 'training outside the US is not up to standard", (do you include Europe, Canada, Japan, Ozealand in that too?) and discussion of national standards is, I predict, going to become a pivotal matter in this whole affair so I suggest this is exactly the right place to discuss it.
I gather there is a freakish viewpoint out there that Boeing is responsible to fix the aeroplane so even imcompetent pilots can't crash it but that's so grotesquely unrealistic it's simply laughable. How on earth such weird cotton-wool woo-woo ideas ever got into an aviation forum beats me! This is real life for God's sake, not the bloody Guardian's social pages!

Oggers, I refrained from including ET409 - although it may well prove related I don't think it is wise to include what could be a one-off, that's a poor basis for a general conclusion wheras LionAirs's history of disasters is so long the next one might almost be predictable on a time-passed basis. If Ethiopian were to have another similar I might change my tune.

re your valid concerns about the Ethiopian CAA's state of denial let's not judge them until we see the final report. However given that Ethiopia is a single-party socialist state and the government controls every aspect of life including the CAA and by extension the national airline too I'm not expecting to learn much very from it beyond being long on rhetoric and short on critical facts but we'll just have to wait and see. I sincerely hope I'm proved wrong.

This makes it all the more essential that Boeing appear as open and honest as possible.

[GordonR_Cape]

It may (or may not) be helpful to remember that the autopilot does not require MCAS help.
This reinforces the fact that this is fundamentally a stick feel issue rather than a critical instability that could kick in under extreme but still in certified envelope conditions.

An interesting point! I can only assume that this has something to do with the autopilot not using AOA as an input like MCAS does, but rather gyro pitch (and other parameters).

I previously asked the question: How could the autopilot ever get into a high AOA situation? One answer was if the autothrottle is disabled. The implication being that the autopilot could keep increasing the nose up pitch until the stall warning activates, and the crew intervenes. I hope that scenario has been carefully tested?

This also touches on the question of whether the MAX autopilot was specifically programmed for the region of high AOA characteristics covered by MCAS, and whether it was tested under actual flight conditions?

[MurphyWasRight]

An interesting point! I can only assume that this has something to do with the autopilot not using AOA as an input like MCAS does, but rather gyro pitch (and other parameters).

I previously asked the question: How could the autopilot ever get into a high AOA situation? One answer was if the autothrottle is disabled. The implication being that the autopilot could keep increasing the nose up pitch until the stall warning activates, and the crew intervenes. I hope that scenario has been carefully tested?

This also touches on the question of whether the MAX autopilot was specifically programmed for the region of high AOA characteristics covered by MCAS, and whether it was tested under actual flight conditions?
It may be simpler than that, of course I could be wrong on autopilot details.

The autopilot 'knows' the desired column (and other controls) positions and puts them there, it does not rely on column feel for feedback.

It is manipulating the controls to achieve the desired aircraft state, when pitch is low set column position back until pitch OK at a defined 'gain', how much (not 'how hard) to pull is based on divergence.
This a classic feedback loop, the stick force is not part of the loop.

An imperfect analogy is cruise control in a car, it maintains desired speed directly whereas the driver uses more or less force on the accelerator to maintain speed.

Given the above I would assume (a tricky word in many fields) that no significant changes to autopilot for MAX were required, at most some tweaking of gains.

When I said 'critical' instability i referred to something like reversal of effect past a certain point or similar which would be catastrophic in a feedback loop.

[ams6110]

@meleagertoo
To take a contrarian viewpoint: If an aircraft is not safe to be operated by airlines in countries whose pilots are not top-notch, then it should not be sold to those airlines/countries. Or fix the aircraft, so that it is safe to be operated by less-than-perfect pilots. End of (my version of) the story...


My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.

[737 Driver]

I previously asked the question: How could the autopilot ever get into a high AOA situation? One answer was if the autothrottle is disabled. The implication being that the autopilot could keep increasing the nose up pitch until the stall warning activates, and the crew intervenes. I hope that scenario has been carefully tested?



In the 737 as well as every other aircraft I have flown, the autopilot will attempt to do exactly what you told it do - until it can’t. It then disconnects with whatever alerts that it provides at whatever trim state and power settings were in place. This will often result in the pilots suddenly having to take command of an aircraft that is in, to use the popular euphemism, an “undesired aircraft state.” This can potentially be a very shocking moment.

Even when the autopilot is in use, at least one of the pilots is expected to actively monitor the aircraft. If the autopilot is struggling, then there will be signs depending on what exactly the problem is. The pilot is then expected to intervene and correct the problem. Until the technology progresses to a point that this active monitoring role is no longer needed, this is not a “design” issue, it is a pilot training issue.

[gums]

Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...

[meleagertoo]

My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.

Amen to the gist of that, but it isn't fair or reasonable to describe anything "unsafe" if it comes to harm through excessive mishandling. A Moscow bus isn't in itself unsafe because the driver's necked a quart of Stolly, is it?

[Lost in Saigon]

Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...

I think your interpretation is wrong.

My understanding is that MCAS was implemented ONLY to satisfy FAA Section 25.173


25.173 Static longitudinal stability.

Under the conditions specified in § 25.175 (https://www.law.cornell.edu/cfr/text/14/25.175), the characteristics of the elevator control forces (including friction) must be as follows:

(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or VFC/MFC, whichever is appropriate, or lower than the minimum speed for steady unstalled flight.

(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in § 25.175 (https://www.law.cornell.edu/cfr/text/14/25.175) (a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in § 25.175(b) (https://www.law.cornell.edu/cfr/text/14/25.175#b), when the control force is slowly released from any speed within the range specified in paragraph (a) (https://www.law.cornell.edu/cfr/text/14/25.173#a) of this section.

(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.

(d) Within the free return speed range specified in paragraph (b) (https://www.law.cornell.edu/cfr/text/14/25.173#b) of this section, it is permissible for the airplane (https://www.law.cornell.edu/cfr/text/14/25.173), without control forces, to stabilize on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.

This link provides some good information. 737 MAX Maneuvering Characteristics Augmentation System (MCAS) (http://www.b737.org.uk/mcas.htm)

"MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation."

[Water pilot]

My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.
What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.

[Organfreak]

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.

As outlined countless times by 737 Driver, attention to pitch and power would have saved the day in both cases. Why is that so difficult?

[GlobalNav]

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.
One question should be whether the manufacturer was really aware of the “flaw” or even characterized it as such. If so, it would be unconscionable not to design it out. To have a known flaw and then presume pilots will find a some way to overcome it (without even telling them about it) is crazy. That is not engineering and it is not the Boeing of old.

I suspect that the combination of events following the particular malfunction of AOA sensor on MCAS was not foreseen, which I am afraid would be a flaw in the engineering. Regardless, now they know and they ought to do more than tweak the software. This failure mode was twice demonstrated to be catastrophic and the redesign must make it extremely improbable. Will they?

[Lost in Saigon]

My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.



What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.


"stick and rudder, pitch and power" also means basic airmanship. Basic airmanship also involves keeping your aircraft in trim at all times.

In both accidents the pilots were unable to properly deal with a stick shaker at takeoff. Basic airmanship would dictate not raising the flaps when faced with a stick shaker at takeoff. That act lone should have saved the day.

[AAKEE]

Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...

Lost in Saigon is correct. I’ll ad some to his post:
If there really was a pitch up moment at high AoA/stall that is not an acceptable behaviour and in that case the model would need a stick pusher to keep it from getting there.( § 25.203 Stall characteristics )

Also, if the Max had a pitch up moment, the MCAS downtrimming of the stab could easily be overridden by more elevator( elevator pitch up canceling out the stab downtrim) making sum= status quo. Then the pitch up moment still would be there. If there was a pitch up moment it could only be fixed with a stick pusher.

There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down comming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.

Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)

[alf5071h]

… attention to pitch and power would have saved the day in both cases. Why is that so difficult?
Pitch / power is an aspect of UAS drill, which was diagnosed immediately after takeoff and managed by the crew as they saw the situation.
You and others appear to misunderstand the operation of MCAS trim and control power of the tail.
Once the flap retracted, MCAS started to apply nose down trim, 9 sec on, 5 sec off. There are no additional alerts to indicate that MCAS would generate unwanted trim inputs - no forewarning; thus the only cue was a change in stick force (not looking at the trim wheel). This in part was counteracted by manual trim, which was the crew’s initial and then continuing attempt to manage pitch.

The consensus, but not authoritative view is that pilot electric trim does not override MCAS; thus the summed tail trim movement is nose down at high rate. With increasing tail trim the counteracting electric trim may be progressively ineffective (summed tail forces), similarly the reduced manual trim wheel operation after electric trim is inhibited.
At some point it is likely that the elevator power, stick forces, reach a condition where further pitch control is unavailable. There are no conventional piloting skills which will be able to ‘fly the aircraft’.

Basic airmanship would dictate not raising the flaps when faced with a stick shaker at takeoff. That act lone should have saved the day.
No aspect of airmanship would ensure that flaps were not retracted. You assume that the crew had deduced the possibility of MCAS problems; but they could have been highly focussed on flying the aircraft with UAS. There were no warnings indications to the possibility of trim problems; no change with flaps up.
Check your assumptions; provide a supporting argument for alternative views.

…, if the Max had a pitch up moment, the MCAS downtrimming of the stab could easily be overridden by more elevator( elevator pitch up canceling out the stab downtrim).
There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down comming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.

Re elevator forces, see above.
Your appreciation of aerodynamics, controls, cg, etc, differs from mine, and I suspect many other aviators.

[Lost in Saigon]

The consensus, but not authoritative view is that pilot electric trim does not override MCAS; thus the summed tail trim movement is nose down at high rate. With increasing tail trim the counteracting electric trim may be progressively ineffective (summed tail forces), similarly the reduced manual trim wheel operation after electric trim is inhibited.
At some point it is likely that the elevator power, stick forces, reach a condition where further pitch control is unavailable. There are no conventional piloting skills which will be able to ‘fly the aircraft’.



The consensus is WRONG. Boeing clearly states that electric trim will STOP and even REVERSE unwanted MCAS operation.


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1108x735/005a_df504822cfd83368285cf165d09a74eb48a20fdc.jpg

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1377x614/005aa_412cf407160beaf5177cd0f133d02ff7d3da7204.jpg

[slacktide]

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly,

Yes, it was. The "automatics" failed by providing undesired and uncommanded control inputs, but this was not the initiating failure that the pilots failed to react to. MCAS did not become a factor until a full minute and fifteen seconds into the flight. The inital failure that was presented to the pilots was stickshaker on takeoff with UAS. Rather than manually flying the aircraft using pitch and power as required by the memory items on the UAS NNC checklist, the accident pilots tried to re-engage the autopilot multiple times, and relied on the autothrottle to manage power, which put them above VMo. This directly contradicts the UAS NNC checklist which has the pilots disengage the autopilot, autothrottle, and flight director as memory items for the first three steps, and further goes on to state "Do not use the the autopilot, autothrottle, or flight directors." Look at the timeline:

5:37:34 ATC clears flight for takeoff
5:38:44 (just after liftoff) AOA disagree, airspeed disagree, altitude disagree, and stickshaker are indicated in FDR
5:38:46 Master Caution light illuminates.
5:38:58 Pilots attempt to engage autopilot
5:39:00 Pilots attempt to engage autopilot
5:39:22 Pilots successfully engage autopilot
5:39:45 Flap retraction begins
5:39:55 Autopilot disengages
5:40:00 MCAS begins MCAS-ing

So, it was a minute and fifteen seconds between the initial indication of a failure, and the undesired, uncommanded trim input. During that time, the pilots did not execute a single step of the UAS NNC checklist that they should have been following from memory. But they sure spent a lot of time heads-down button-pushing that autopilot. It's clear that they were not comfortable manually flying the aircraft as the checklist requires. To be noted, until 5:40:00, the airplane would have been behaving exactly as an NG would during the same type of AOA vane failure, and the procedure to follow during UAS is identical.

[bill fly]

Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...

Hi Gums, Hope the dentist was kind... Saw the charts before, ta.

I think the point is:

- As they say on the news (and here for once they are right...) MCAS is a function which can/will push the nose down whereas

A feel increase mechanism will make pulling back harder - but won’t push the nose down.

Now I know which I would rather have.

Let’s imagine that such a system had been fitted instead of MCAS in the three AoA anomaly cases which we have discussed. What would have happened?

All the accompanying warnings for stall and speed disagree etc. would still have gone off. While the crew were sorting this out - with or without autopilot, with or without flap - there would have been no further distraction except a stiffer pull force, which could have been trimmed out as required. No big hand forcing the flight path down - no trim “runaway”.

The chances for survival would have been good, crew skills here or there I reckon.

Greetings, B

[groundbum]

Hi Gums, Hope the dentist was kind... Saw the charts before, ta.

I think the point is:

- As they say on the news (and here for once they are right...) MCAS is a function which can/will push the nose down whereas

A feel increase mechanism will make pulling back harder - but won’t push the nose down.

Now I know which I would rather have.

Let’s imagine that such a system had been fitted instead of MCAS in the three AoA anomaly cases which we have discussed. What would have happened?

All the accompanying warnings for stall and speed disagree etc. would still have gone off. While the crew were sorting this out - with or without autopilot, with or without flap - there would have been no further distraction except a stiffer pull force, which could have been trimmed out as required. No big hand forcing the flight path down - no trim “runaway”.

The chances for survival would have been good, crew skills here or there I reckon.

Greetings, B

this for me is THE best post on this entire thread

G

[slacktide]

Pitch / power is an aspect of UAS drill, which was diagnosed immediately after takeoff and managed by the crew as they saw the situation.

Please show us where in the preliminary report timeline that the crew diagnosed the UAS, and took any action that was consistent with following the UAS NNC checklist.
https://leehamnews.com/wp-content/uploads/2019/04/Preliminary-Report-B737-800MAX-ET-AVJ.pdf

[gums]

Salute!

Great discussion.
I gotta get one of our test pilot golden arms to talk a bit.
While I go thru old stuff discussing the pitch moments of the 737, I will leave you a few thots.

Unless you only wish to change what the pilot feels, you do not screw around with the largest aero surface on the plane besides the main wing. You screw around with the artificial feel system. GASP!!

Pushers are not a really neat fix when all you want to do is reduce the nose up pitching moment. You have to deal with the aero as well as the artificial feel system.. And before more research and consulting, I comment:

The Airbus FBW in 320 plus does not give a rat’s about the “feel” close to a stall AoA. You can command max or min and that stick has the same spring force as if you were in a dogfight in the F-22 or Typhoon. Huh? It was certified because the basic aero met the criteria and the plane design would do just fine with ropes, levers, pulleys, pushrods and such. That was not what I flew in the Viper, due to inherent stability designed in from day one. But I can use my experience using a stick with zero feedback, and it commanded roll rate and gee according to how many pounds I exerted on the thing (Airbus stick is displacement mainly, but Viper was all pressure sensors)

PEI..... We need some test community inputs to this discussion

Gums.....
P.S. tanks for tolerating this old fart that flew ropes, pulleys and then hybrids and finally no sierra FBW that had zero mechanical anything before some here were born.

[YYZjim]

Who owns the CVR and FDR data?

A complete CVR transcript would shed a lot of light on the question of whether or not an MCAS runaway is beyond the capability of the average MAX pilot. A complete FDR dataset would fill in some of the blanks that continue to cause confusion and argument. Many posters say, "Let's wait for the final report."

Waiting is not an acceptable option for Boeing and their MAX-customers.

Does anyone know if Boeing/FAA/NTSB have seen the complete CVR and FDR data?

The Ethiopean government's secrecy in the early days of the investigation suggest that they are not in the mood for sharing. International law entitles them to run the investigation. Does it also allow them to hide the data?

YYZjim

[sadtraveller]

Not a 737 driver so I have no vested interest in defending my plane/livelihood. Also neither American nor European, so I could not care less about defending my "team". What I am is a frequent traveller who would prefer not to become a smoldering crater in the ground -- preferably not even if I am flying on a plane flown by the most poorly trained, least-skilled and most sleep-deprived (but properly licensed) pilot.

I've read this whole thread and then some, and thus far my reading of the facts of these incidents is as follows:

1. (Fact) Boeing was caught with their pants down by the A320neo and needed to come up with a quick 737 update with better fuel economy (i.e. with minimal engineering changes).

2. (Fact) Rather than produce a clean-sheet design or update the 737 undercarriage/wings to incorporate an extended main landing gear, Boeing extended the nose gear and bolted on larger engines by moving the engines forward relative to COG, in spite of the negative impact that this had on aircraft stability/handling.

3. (Fact) The 737 stabilizer has much greater vertical authority than the elevator (I have seen estimates of about 3x as much)

4. (Fact) Due to the enlarged and forward-positioned engines, the Max exhibits poor aerodynamic/flight handling characteristics (tendency to pitch up) at high AOA when approaching stall. As communicated by at least one purported Boeing engineer much further up this thread (post 1000 or thereabouts?), this tendency to pitch up is so extreme that elevator input alone would not have been sufficient to make the aircraft adequately controllable, hence why a stick pusher was considered and rejected.

5. (Speculated) For the same reason, once in a stall, the 737 Max is quite likely to be extremely difficult to bring back under control through normal control surface inputs, without the rapid application of an extreme amount of stab trim (i.e. by MCAS). (Has anyone flown a Max into a stall at MTOW/rear COG and would they be able to provide input on whether it is possible to bring it back under control without trim input/MCAS?)

6. (Fact) The FAA/other authorities require positive elevator feel at high AOA to provide stall protection.

7. (Fact) MCAS is designed to provide positive elevator feel at high AOA to meet regulator requirements.

8. (Fact, deduced from 6 and 7) MCAS provides stall protection.

9. (Fact) The certified limit of MCAS authority (one burst of 0.6 deg) was also not sufficient to make the aircraft adequately controllable at high AOA. Boeing increased MCAS authority to 2.5 degrees per cycle, with an unlimited number of allowed cycles, without informing regulators/obtaining certification.

10. (Fact) The FAA was so understaffed/feckless that they did not discover/were not made aware of this severe deviation from certification.

11. (Fact) Based on various pilot reports and according to archaic 737 manuals and flight training, past a certain limit that is inversely related to airspeed, manual authority over trim is impossible for pilots of less than super-human strength, so e trim is the only option available.

12. (Fact) Boeing shrunk the size of the Max trim wheel, reducing leverage and further increasing strength required to manually trim. They failed to inform regulators of this change.

13. (Fact, deduced from numbers 10 and 3) Under certain portions of the flight envelope, pilots lose all vertical authority without electric trim.

14. (Opinion) Based on its essentiality to maintaining vertical authority under all allowed portions of the flight envelope, electric trim should be considered a safety-critical component and should be subject to all of the requirements thereof (e.g. redundant computers, motors, etc.)

15. (Fact) Boeing redesigned the cutoff switches to make it impossible to disable MCAS without also disabling e trim. They then failed to describe these changes in the manual or provide this information to pilots.

16. (Unverified, but extremely likely) Based on the inconsistent application of upward electric trim by the pilots during the two accidents, something was likely preventing the pilots from continuously applying upward trim. If your life is flashing before your eyes and you are battling to get your aircraft to climb, your thumb is going to be glued to the trim switch, not making the bare minimum in small (and inconsistent) blip applications. As far as I know it has not been conclusively reported, but it appears that based on the trim traces that MCAS is in fact capable of overriding thumb trim and not the other way around, despite claims to the contrary.

17. (Speculation) Many have speculated that the electric trim motor is also incapable of controlling the stabilizer under certain portions of the flight envelope (e.g. high speed, extreme trim, opposing elevator). If this is true, then there are actually portions of the flight envelope in which pilots lose all vertical authority even if electric trim is operational.

18. (Opinion) If there are regions of the 737 flight envelope (e.g. extreme trim, opposing elevator) under which pilots lose vertical authority, the whole 737 fleet, both maxs and NGs (assuming that they are also affected by the same issue), should be grounded until such a time as trim deflection is mechanically limited to prevent entry into these uncontrollable regions of the flight envelope.

19. (Fact) Boeing did not advise pilots of the limits of manual trim authority or the need to e trim to neutral before cutting the trim switches.

20. (Fact) Boeing decided to base the activation of MCAS on a single AOA sensor (rather than making use of the two installed sensors) and a single computer, without even basic sanity checking.

21. (Fact) A large number of recent reports have identified safety-critical manufacturing defects and foreign object debris in recently-constructed Boeing aircraft as a result of lax manufacturing standards, and articles from yesterday indicate that a whistleblower reported to the FAA on April 5th that FOD had resulted in damage to Max AOA wiring in at least one instance.

22. (Fact) Boeing did not inform airlines or pilots about MCAS, did not include it in the manual, and did not provide any MCAS related training.

23. (Fact) Boeing chose not to provide an aural/visual MCAS activation warning.

24. (Fact) Boeing opted to sell the AOA indicator display as an optional extra rather than a built-in safety feature.

25. (Fact) Boeing disabled the AOA disagree warning for customers who did not purchase the optional AOA indicator display. Previous 737 models had functional AOA disagree warnings. As reported recently by the SWA pilots assoc, Boeing did not inform airlines/pilots of this change.

26. (Fact) Boeing did not make or arrange for the production of an adequate number of Max simulators, hence the extreme resistance to any changes that would require sim training.

27. (Fact) Pilots did not receive any information about MCAS or sim/flight training for dealing with a possible MCAS activation prior to these incidents (they did not even know that the system existed).

28. (Inferred based on events) The incident pilots were inadequately trained to handle and responded very poorly to MCAS activation incidents. (Note: is it the pilots' fault that they were inadequately trained on a system that they did not know existed on simulators that were not available?)

29. (Fact) After the Lion air accident, Boeing provided only the bare minimum in information regarding MCAS and refused to acknowledge any problem with the plane, placing the blame entirely on the dead pilots.

30. (Fact) After the Ethiopian accident, Boeing resisted efforts to ground the aircraft and refused to acknowledge any problem with the plane, again placing the blame entirely on the dead pilots.

31. (Fact) After the Ethiopian incident and following a meeting between Muilenburg and Trump, Trump's FAA stooge resisted requests to ground the Max.

32. (Fact) Only after foreign regulators began grounding the Max en masse did the FAA also follow suit and ground the Max.

33. (Fact) Boeing, as evidenced by Muilenburg's recent press conference, still refuses to acknowledge any problem with the plane, and continues to place blame solely on the dead pilots. Meanwhile they are working on a software "improvement" for MCAS, without any reports of hardware fixes in the works.

Conclusion:

In my opinion, Boeing has acted disgracefully in this situation and should be prosecuted criminally for manslaughter (perhaps this is an opportunity for Barr to prove that he is not a Trump stooge). Meanwhile the FAA has been completely compromised and corrupted by the kleptocracy that is taking over America. These are systemic failings rather than a one-off incident, and they raise the question of how many other similar failures remain lurking in the shadows due to negligent management practices and oversight in a country that is rapidly losing any respect for the rule of law. No outcome short of a complete (and transparent) overhaul of Boeing's safety culture, prosecution and incarceration of senior management, and possibly even a break-up of the company (e.g. splitting off commercial aviation from defense) will make me comfortable flying on any recently-produced Boeing metal. I'll be putting my money where my mouth is by exclusively booking Airbus until these changes are made. I'm not holding my breath, so it looks like I'll be flying Airbus for some time to come.

[Hot 'n' High]

Edit - Gums (and also Bill Fly) - just seen your Post 4706 when I Posted - but as I've written this forgive me for Posting anyway. Exactly! You and I are together I think on this! (If I may be so bold as to assume that?) :ok:

...........

There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down coming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.

Never flown (or fixed) Boeings but, given the above which is what I think we all agree is the issue – not enough stick force at higher AoA to meet Certification due to the pitch-up moment generated by the donks homes - then surely this Thread (https://www.pprune.org/questions/429053-b737-feel-centering-unit.html) describes where the solution should have been implemented to “reprofile” Elevator Feel but for Speed and AoA rather than just for Speed – in other words, add in a bit more "aft" stick Q-resistance at high AoA.

While, ideally using a dual AoA system, if Boeing insisted on just one AoA feed, all you would have is a slightly erroneous “feel profile” at higher AoAs with a U/S AoA system (auto cured when the AoA system is fixed). This would seem far more manageable (tho it would be out of Certification limits in purist terms on AoA fail) than the MCAS erroneously trimming AND which materially affects the flightpath (and I’m deffo going to avoid any discussions on whether or not that was handleable by an “average crew” - whatever one of those is – but we do have 2 jets down with awful consequences for 100’s of people so the complete system (incl aircrew and bits and software) fell over twice).

Is that assessment correct and did MCAS seem to provide Boeing with a simpler/cheaper solution to “emulate” a change in Q rather than make changes to the Elevator Feel Computer (EFC) in it’s role as described by IFixPlanes? I can’t really recall this discussion of the EFC anywhere. Or, since that Thread was wayyy back in 2010, does the EFC no longer exist – but since Q-feel has been around for ever really - something still does that job surely. Boeing seems to be trying to keep the aircraft away from high AoA so that we don't get uncertifiable Q issues rather than sorting Q so it's certified at all AoAs. I can’t recall where the schematics appear in this thread re an EFC but just a thought … and happy to crawl back into my box if talking utter tosh! Won’t be the first time for me!

...........

Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)

And “Here, here!” - always good to see Gums chipping in for the reasons above! :ok:

[slacktide]

737Driver and his cohorts seem intent on diverting attention towards alleged deficiencies in the airmanship of the crews of the two 737 max aircaft that crashed rather than dealing with the real villains of the piece, namely, the FAA and Boeing.

This is a hazardous attitude which is harmful to aviation safety. Pointing out that the pilot's actions were seriously deficient in no way exonerates Boeing. It is clear that Boeing's design of MCAS appears to be the primary cause of both accidents, it is unacceptable, it needs to be fixed, and it is being fixed. However you cannot fix only one deficient link in an accident chain and declare "Mission Accomplished!" like you are George W. Bush on an aircraft carrier after the first battle in the Iraq war. ALL deficiencies that contributed to the accident need to be assessed to determine if corrective action is needed. This could include the regulations that the aircraft is designed to, the oversight of the certification and change management process by the regulator, the content and method of delivery of the NG to MAX transition training, the schedule, recency, and frequency of any recurring training, the service bulletin and FCOM/QRH deployment procedures at the airline, and the maintenance and post-maintenance test procedures at the airline. (Lionair - so far there have been no indications that Ethiopian performed maintenance on the AOA or ADIRU)

[SLFstu]

Some posters in this thread have wondered if reliability stats exist for AoA sensors.

Apparently the FAA mandates that for US operators all aircraft faults that require maintenance actions are to be reported within 28 days of occurrence. (Yes, for all items big or small, even for the simplest things such as loose exit signs or a flat battery pack in a FA emergency flashlight!)

CNN (yep, them) went hunting through the public database looking for evidence.

“The FAA has received at least 216 reports of AOA sensors failing or having to be repaired, replaced or adjusted since 2004, according to data from the FAA’s Service Difficulty Reporting website.
Those reports, about one-fifth of which involve Boeing planes, include incidents in which AOA sensors were frozen, improperly installed, struck by lightning or even hit by flying birds. In some cases, faulty sensors led to stall warnings, forcing pilots to abort takeoffs or perform emergency landings.”

More alarming in the CNN article with video (https://edition.cnn.com/2019/04/30/politics/boeing-sensor-737-max-faa/index.html) is the claim that unnamed Boeing sources (ex. a former MAX test pilot) report that the 737MAX series were not tested against AoA failure: "I don't think we appreciated the ramifications of a failure of an AOA probe."
Goes on...(in the expected style).

FAA's Service Difficulty Reporting website (https://av-info.faa.gov/sdrx/Default.aspx) (if you're keen to explore there's a Search Reports link in the left column on the site)

[Hot 'n' High]

................ Pointing out that the pilot's actions were seriously deficient in no way exonerates Boeing. .............. This could include the regulations that the aircraft is designed to, the oversight of the certification and change management process by the regulator, the content and method of delivery of the NG to MAX transition training, the schedule, recency, and frequency of any recurring training, the service bulletin and FCOM/QRH deployment procedures at the airline, and the maintenance and post-maintenance test procedures at the airline. (Lionair - so far there have been no indications that Ethiopian performed maintenance on the AOA or ADIRU)

Agreed! It's called "Systems Engineering" and, in their System Safety Assessment, Boeing assumed a level of performance of the 3 elements of their system Hardware, Software and Humanware all of which was deficient in that all elements did not meet Boeings assumed performance levels on several occasions - hence the holes lining up twice in the Safety Assessment. The holes are meant to line up once every x,000,000 hrs - but they lined up twice in quick succession - the assumed performance levels (reliability) did not provide the level of Safety required - or that it was not fully assessed - a point SFLstu notes above with that quote "I don't think we appreciated the ramifications of a failure of an AOA probe." That is a worry if true! Irrespective of "Well, they [the crew] should have been able to....." I personally suspect the next alignment of all 3 elements failing (one could argue MCAS worked as designed but the design was too "severe") would not have been far away - hence the grounding so we'd have time to consider what needs fixing - as you say, more than just a bit of code. The fact that, IMHO, (and that of at least a couple of other people in recent Posts) that the solution was applied in the wrong area worries me too!

As you say, all elements of the "system" need to be addressed - but, if the Q-system is where the solution should by rights be - sadly that does not seem to be likely. So, the other elements will have to be able to mitigate a bigger Risk(?) posed by MCAS solution than by a Q-system change. Would "Best of a bad job!" be too strong a phrase? And, as you say, not only do we have to make the MAX "system" safe (which we can do), we have to (re)learn how it could have been done better. Using 2 dreadful crashes to decide we as an Industry had got things wrong is not the way to do things. We should all think long and hard where, in our own jobs, what the effects could potentially be if we don't play our part in whatever we are involved in (see the thread in the Military forum dealing with Airworthiness for example). Been in aviation 41 years now and the only progress I've made is, each year, I realise that I know even less than I thought I knew last year!

Off to find a non-asbestos fire blanket to hide under so as avoid the flaming I'm sure I'll Rx over this! Oh, and decide whether I'm just so "unsafe" I should retire immediately!

[GordonR_Cape]

Some posters in this thread have wondered if reliability stats exist for AoA sensors.

Apparently the FAA mandates that for US operators all aircraft faults that require maintenance actions are to be reported within 28 days of occurrence. (Yes, for all items big or small, even for the simplest things such as loose exit signs or a flat battery pack in a FA emergency flashlight!)

CNN (yep, them) went hunting through the public database looking for evidence.

Similar links have been posted on the forum. The Washington Post previously did a count over a different timeframe, and gets to the point. My emphasis added: https://www.washingtonpost.com/business/economy/sensor-cited-as-potential-factor-in-boeing-crashes-draws-scrutiny/2019/03/17/5ecf0b0e-4682-11e9-aaf8-4512a6fe3439_story.html (https://www.washingtonpost.com/business/economy/sensor-cited-as-potential-factor-in-boeing-crashes-draws-scrutiny/2019/03/17/5ecf0b0e-4682-11e9-aaf8-4512a6fe3439_story.html?utm_term=.ebb98a5e06ed)
Angle-of-attack sensors have been flagged as problems more than 50 times on U.S. commercial airplanes over the past five years, although no accidents have occurred over millions of miles flown, according to reports made to the Federal Aviation Administration’s Service Difficulty Reporting database. That makes it a relatively unusual problem, aviation experts said — but also one with magnified importance because of its prominent role in flight software.

[wheelsright]

The consensus is WRONG. Boeing clearly states that electric trim will STOP and even REVERSE unwanted MCAS operation.



Unfortunately, Boeing cannot be relied on as providing full and accurate information. The investigation and further legal actions will have to resolve how the systems actually works. There may be an assumption that electric trim input will override MCAS authority but it is not entirely clear how the system operates with conflicting demands. How the authority is resolved during conflict will have to be resolved fully. There are software, electrical, mechanical and aerodynamic elements to the investigation of the trim system.

Obviously, continuing to rely on conflicting AoA sensors is inherently wrong. MCAS should be disabled automatically if the primary sensor information is known to be unreliable. Boeing were aware of the defect even before the Lion Air incidents, or even at the design stage, but chose not eliminate the defect. The question is why did Boeing act in that way and to what degree they tried to conceal or underplay the issues. The Max MCAS system is poorly designed and inherently dangerous. It has passed through many hands, but for some reason, obvious problems were not addressed or may have been concealed. It is certainly possible that persons in Boeing and in the FAA will be held to account. In those circumstances, there is good reason doubt the accuracy of information that Boeing provides.

While accident investigations generally avoid attributing or proportioning blame, the courts will have to do precisely that. No doubt the pilots could have done better, but were not the primary cause. Boeing are facing some very difficult questions along with the FAA.

[slacktide]

Apparently the FAA mandates that for US operators all aircraft faults that require maintenance actions are to be reported within 28 days of occurrence. (Yes, for all items big or small, even for the simplest things such as loose exit signs or a flat battery pack in a FA emergency flashlight!)

This is not quite correct. Only a subset of items and events are subject to mandatory SDR reporting. The applicable regulation is 14 CFR Part 121.703. It is DEFINITELY not applicable to all items big or small. A loose exit sign, or a flat battery pack in a flashlight would require an SDR because they are part of the passenger emergency evacuation lighting systems, which is listed in 121.703. A loose bathroom sign or a flat battery pack in the in-flight entertainment system would not require an SDR.

An inoperative AOA sensor that did not require the crew to take an emergency action would not require a SDR to be submitted. I read a few of the AOA SDR reports, and they were all associated with conducting a rejected takeoff. The takeaway here is that AOA failure rates may be higher than indicated by the SDR database.

edit: Technically, even an AOA failure that caused an RTO would not require an SDR to be submitted. Bullet (16) would be applicable - "Aircraft components or systems that result in taking emergency actions during flight", and 121.703 defines "during flight" as after the wheels have left the ground.

[MurphyWasRight]

:
Originally Posted by Lost in Saigon https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/showthread.php?p=10460650#post10460650)
The consensus is WRONG. Boeing clearly states that electric trim will STOP and even REVERSE unwanted MCAS operation.


Unfortunately, Boeing cannot be relied on as providing full and accurate information. The investigation and further legal actions will have to resolve how the systems actually works. There may be an assumption that electric trim input will override MCAS authority but it is not entirely clear how the system operates with conflicting demands. How the authority is resolved during conflict will have to be resolved fully. There are software, electrical, mechanical and aerodynamic elements to the investigation of the trim system.
...
...
.
Alll 3 of the FDR traces clearly show MCAS kicking in ~5 seconds after the last manual electric trim. The ET trace also shows MCAS stopped in it's second run by pilot trim at 05:40:27. This is exactly as Boeing describes it.

On a separate note, it is only the manual (wheel) trim that is suspected of being inoperable with high aero loads. (not just at >VMO).
The electric trim will work, and even if the motor stalled the inputs would still show on the FDR, in the same way that the MCAS input in ET at 05:40:15 had no effect on trim due to stab trim cutout.

The pilots electric trim inputs (if any) would not show due to the wiring of the cutout switches that remove 28Vdc to them.

[LowObservable]

Everyone who says that ANU input on the tumb switches will reverse MCAS is right.

However, the question is whether training was remotely adequate to address the AND authority of MCAS, which demanded an unusual amount of ANU trim in the teeth of stick-shake, AoA warnings and UAS advisory. Anyone is free to correct me, but it seems as if an unusual amount of thumb-switch ANU would be needed.

Meanwhile, the intermittency of MCAS inputs seems to be tailor-made to look unlike a runaway. It certainly doesn't serve to decrease confusion.

[slacktide]

However, the question is whether training was remotely adequate to address the AND authority of MCAS, which demanded an unusual amount of ANU trim in the teeth of stick-shake, AoA warnings and UAS advisory. Anyone is free to correct me, but it seems as if an unusual amount of thumb-switch ANU would be needed.

This is one thing that has confused me in both accidents - not using the manual trim switches to return the aircraft to a fully trimmed condition. Even in a private pilot training syllabus, this is taught and demonstrated as part of the very first introductory flight lesson, and it is not a particularly difficult concept to grasp (but mastering it takes time...) Over time recognizing when you will need to trim, and how much trim is needed to adjust the control pressure, just becomes instinctual.

Can any of our resident 737 pilots comment on use of manual electric trim and control pressures in that aircraft? Is the process similar to on a light aircraft, where you trim until you are satisfied that the aircraft can be controlled with only light fingertip pressure? How does an active stickshaker affect your ability to perceive control pressure?

[WillFlyForCheese]

I think your interpretation is wrong.

My understanding is that MCAS was implemented ONLY to satisfy FAA Section 25.173

* * *

"MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation."

I've been thinking about this - and don't believe it can be an accurate statement of the purposeful design of the system. Here's why . . .

MCAS will, when data input dictates, trim AND. It will do so for 9 seconds or so - and then take a 5 second break. When it's taking its break - it's not fulfilling the purpose of 25.173 - right?

If the purpose of the system is to compensate for stick feel - it wouldn't take a break - because the lift generated by the cowlings doesn't take a break.

If tdracer is still around on this topic - I'd like to know how the designed 5-second stand down plays into the purposeful design of the system. It just doesn't make sense to me.

[Thrust Augmentation]

Regardless of whether pilot, training, sensor, computing, hardware or maintenance error caused the incident, to go back to square one I'm still interested in why MCAS was implemented in the 1st place to resolve a feel issue(?).

I understand why the cowlings are larger.

I understand why the cowlings have been repositioned.

I understand why the cowlings increase lift.

I believe that certification requires increasing stick forces at increasing AOA.

I still do not understand why MCAS was the resolution as I still do not understand why the driving one of the 737's most powerful control surface was considered as a suitable remedy to what in my understanding is a pilot perception requirement that certification demands. There are other methods of doing this that cannot put an aircraft in jeopardy.

PLEASE someone tell me that my train of though is wrong, or if it isn't why was MCAS seen by Boeing & the regulators as a suitable resolution to the issue?


I've asked as much a few times previously without reply - I'm genuinely interested & if it wasn't for the fact that there are various MAX threads on the go I would start one specifically on this question.

[GordonR_Cape]

I've been thinking about this - and don't believe it can be an accurate statement of the purposeful design of the system. Here's why . . .

MCAS will, when data input dictates, trim AND. It will do so for 9 seconds or so - and then take a 5 second break. When it's taking its break - it's not fulfilling the purpose of 25.173 - right?

If the purpose of the system is to compensate for stick feel - it wouldn't take a break - because the lift generated by the cowlings doesn't take a break.

If tdracer is still around on this topic - I'd like to know how the designed 5-second stand down plays into the purposeful design of the system. It just doesn't make sense to me.

There are two followup aspects to your question, depending on the version of MCAS 1.0 and MCAS 2.0:
- MCAS 1.0 was designed to satisfy the criteria that you describe, though not smoothly, due to the 5 second pause.
- MCAS 2.0 may remove the option of repeated trim during the same high AOA "event", depending on the definition of event. This would not satisfy the 25.173 criteria, if it allowed the pilots to do a second pull into the high AOA region, after interrupting MCAS by blipping the stabiliser trim switches.

Long ago I posted this assertion: It is logically impossible to design a system that satisfies both limited MCAS activation and 25.173 criteria simultaneously. One of the two limits has to be broken in some scenarios, for example pilots repeatedly entering the high AOA condition. I have not seen any evidence to contradict my assertion.

[ams6110]

I've been thinking about this - and don't believe it can be an accurate statement of the purposeful design of the system. Here's why . . .

MCAS will, when data input dictates, trim AND. It will do so for 9 seconds or so - and then take a 5 second break. When it's taking its break - it's not fulfilling the purpose of 25.173 - right?

If the purpose of the system is to compensate for stick feel - it wouldn't take a break - because the lift generated by the cowlings doesn't take a break.

If tdracer is still around on this topic - I'd like to know how the designed 5-second stand down plays into the purposeful design of the system. It just doesn't make sense to me.

As the trim moves AND, the pull back feel of the column will become heavier. So in that sense, some AND trim can neutralize the tendency for a lighter feel at higher AoA, bringing the feel into certification compliance. Once the trim has moved enough to offset the pitch-up moment from the engine nacelles, it does not need to continue to move AND and MCAS would, in normal circumstances, stop its trim input. The problem in the two accidents is that the AoA was wildly divergent from normal range due to presumably damaged or missing AoA vane. That is what triggered MCAS to make the full 9-second/2.5 degree AND stab movement. In ordinary manual light, with correct AoA data, MCAS would presumably be making much smaller inputs.

[Alchad]

Not a 737 driver so I have no vested interest in defending my plane/livelihood. Also neither American nor European, so I could not care less about defending my "team". What I am is a frequent traveller who would prefer not to become a smoldering crater in the ground -- preferably not even if I am flying on a plane flown by the most poorly trained, least-skilled and most sleep-deprived (but properly licensed) pilot.

I've read this whole thread and then some, and thus far my reading of the facts of these incidents is as follows:

1. (Fact) Boeing was caught with their pants down by the A320neo and needed to come up with a quick 737 update with better fuel economy (i.e. with minimal engineering changes).

2. (Fact) Rather than produce a clean-sheet design or update the 737 undercarriage/wings to incorporate an extended main landing gear, Boeing extended the nose gear and bolted on larger engines by moving the engines forward relative to COG, in spite of the negative impact that this had on aircraft stability/handling.

3. (Fact) The 737 stabilizer has much greater vertical authority than the elevator (I have seen estimates of about 3x as much)

4. (Fact) Due to the enlarged and forward-positioned engines, the Max exhibits poor aerodynamic/flight handling characteristics (tendency to pitch up) at high AOA when approaching stall. As communicated by at least one purported Boeing engineer much further up this thread (post 1000 or thereabouts?), this tendency to pitch up is so extreme that elevator input alone would not have been sufficient to make the aircraft adequately controllable, hence why a stick pusher was considered and rejected.

5. (Speculated) For the same reason, once in a stall, the 737 Max is quite likely to be extremely difficult to bring back under control through normal control surface inputs, without the rapid application of an extreme amount of stab trim (i.e. by MCAS). (Has anyone flown a Max into a stall at MTOW/rear COG and would they be able to provide input on whether it is possible to bring it back under control without trim input/MCAS?)

6. (Fact) The FAA/other authorities require positive elevator feel at high AOA to provide stall protection.

7. (Fact) MCAS is designed to provide positive elevator feel at high AOA to meet regulator requirements.

8. (Fact, deduced from 6 and 7) MCAS provides stall protection.

9. (Fact) The certified limit of MCAS authority (one burst of 0.6 deg) was also not sufficient to make the aircraft adequately controllable at high AOA. Boeing increased MCAS authority to 2.5 degrees per cycle, with an unlimited number of allowed cycles, without informing regulators/obtaining certification.

10. (Fact) The FAA was so understaffed/feckless that they did not discover/were not made aware of this severe deviation from certification.

11. (Fact) Based on various pilot reports and according to archaic 737 manuals and flight training, past a certain limit that is inversely related to airspeed, manual authority over trim is impossible for pilots of less than super-human strength, so e trim is the only option available.

12. (Fact) Boeing shrunk the size of the Max trim wheel, reducing leverage and further increasing strength required to manually trim. They failed to inform regulators of this change.

13. (Fact, deduced from numbers 10 and 3) Under certain portions of the flight envelope, pilots lose all vertical authority without electric trim.

14. (Opinion) Based on its essentiality to maintaining vertical authority under all allowed portions of the flight envelope, electric trim should be considered a safety-critical component and should be subject to all of the requirements thereof (e.g. redundant computers, motors, etc.)

15. (Fact) Boeing redesigned the cutoff switches to make it impossible to disable MCAS without also disabling e trim. They then failed to describe these changes in the manual or provide this information to pilots.

16. (Unverified, but extremely likely) Based on the inconsistent application of upward electric trim by the pilots during the two accidents, something was likely preventing the pilots from continuously applying upward trim. If your life is flashing before your eyes and you are battling to get your aircraft to climb, your thumb is going to be glued to the trim switch, not making the bare minimum in small (and inconsistent) blip applications. As far as I know it has not been conclusively reported, but it appears that based on the trim traces that MCAS is in fact capable of overriding thumb trim and not the other way around, despite claims to the contrary.

17. (Speculation) Many have speculated that the electric trim motor is also incapable of controlling the stabilizer under certain portions of the flight envelope (e.g. high speed, extreme trim, opposing elevator). If this is true, then there are actually portions of the flight envelope in which pilots lose all vertical authority even if electric trim is operational.

18. (Opinion) If there are regions of the 737 flight envelope (e.g. extreme trim, opposing elevator) under which pilots lose vertical authority, the whole 737 fleet, both maxs and NGs (assuming that they are also affected by the same issue), should be grounded until such a time as trim deflection is mechanically limited to prevent entry into these uncontrollable regions of the flight envelope.

19. (Fact) Boeing did not advise pilots of the limits of manual trim authority or the need to e trim to neutral before cutting the trim switches.

20. (Fact) Boeing decided to base the activation of MCAS on a single AOA sensor (rather than making use of the two installed sensors) and a single computer, without even basic sanity checking.

21. (Fact) A large number of recent reports have identified safety-critical manufacturing defects and foreign object debris in recently-constructed Boeing aircraft as a result of lax manufacturing standards, and articles from yesterday indicate that a whistleblower reported to the FAA on April 5th that FOD had resulted in damage to Max AOA wiring in at least one instance.

22. (Fact) Boeing did not inform airlines or pilots about MCAS, did not include it in the manual, and did not provide any MCAS related training.

23. (Fact) Boeing chose not to provide an aural/visual MCAS activation warning.

24. (Fact) Boeing opted to sell the AOA indicator display as an optional extra rather than a built-in safety feature.

25. (Fact) Boeing disabled the AOA disagree warning for customers who did not purchase the optional AOA indicator display. Previous 737 models had functional AOA disagree warnings. As reported recently by the SWA pilots assoc, Boeing did not inform airlines/pilots of this change.

26. (Fact) Boeing did not make or arrange for the production of an adequate number of Max simulators, hence the extreme resistance to any changes that would require sim training.

27. (Fact) Pilots did not receive any information about MCAS or sim/flight training for dealing with a possible MCAS activation prior to these incidents (they did not even know that the system existed).

28. (Inferred based on events) The incident pilots were inadequately trained to handle and responded very poorly to MCAS activation incidents. (Note: is it the pilots' fault that they were inadequately trained on a system that they did not know existed on simulators that were not available?)

29. (Fact) After the Lion air accident, Boeing provided only the bare minimum in information regarding MCAS and refused to acknowledge any problem with the plane, placing the blame entirely on the dead pilots.

30. (Fact) After the Ethiopian accident, Boeing resisted efforts to ground the aircraft and refused to acknowledge any problem with the plane, again placing the blame entirely on the dead pilots.

31. (Fact) After the Ethiopian incident and following a meeting between Muilenburg and Trump, Trump's FAA stooge resisted requests to ground the Max.

32. (Fact) Only after foreign regulators began grounding the Max en masse did the FAA also follow suit and ground the Max.

33. (Fact) Boeing, as evidenced by Muilenburg's recent press conference, still refuses to acknowledge any problem with the plane, and continues to place blame solely on the dead pilots. Meanwhile they are working on a software "improvement" for MCAS, without any reports of hardware fixes in the works.

Conclusion:

In my opinion, Boeing has acted disgracefully in this situation and should be prosecuted criminally for manslaughter (perhaps this is an opportunity for Barr to prove that he is not a Trump stooge). Meanwhile the FAA has been completely compromised and corrupted by the kleptocracy that is taking over America. These are systemic failings rather than a one-off incident, and they raise the question of how many other similar failures remain lurking in the shadows due to negligent management practices and oversight in a country that is rapidly losing any respect for the rule of law. No outcome short of a complete (and transparent) overhaul of Boeing's safety culture, prosecution and incarceration of senior management, and possibly even a break-up of the company (e.g. splitting off commercial aviation from defense) will make me comfortable flying on any recently-produced Boeing metal. I'll be putting my money where my mouth is by exclusively booking Airbus until these changes are made. I'm not holding my breath, so it looks like I'll be flying Airbus for some time to come.

What a truly superb analysis. I suspect this could very well be plaigerised in its entirety and feature in various court cases in the future.

Regards

[dingy737]

Yes, it was. The "automatics" failed by providing undesired and uncommanded control inputs, but this was not the initiating failure that the pilots failed to react to. MCAS did not become a factor until a full minute and fifteen seconds into the flight. The inital failure that was presented to the pilots was stickshaker on takeoff with UAS. Rather than manually flying the aircraft using pitch and power as required by the memory items on the UAS NNC checklist, the accident pilots tried to re-engage the autopilot multiple times, and relied on the autothrottle to manage power, which put them above VMo. This directly contradicts the UAS NNC checklist which has the pilots disengage the autopilot, autothrottle, and flight director as memory items for the first three steps, and further goes on to state "Do not use the the autopilot, autothrottle, or flight directors." Look at the timeline:

5:37:34 ATC clears flight for takeoff
5:38:44 (just after liftoff) AOA disagree, airspeed disagree, altitude disagree, and stickshaker are indicated in FDR
5:38:46 Master Caution light illuminates.
5:38:58 Pilots attempt to engage autopilot
5:39:00 Pilots attempt to engage autopilot
5:39:22 Pilots successfully engage autopilot
5:39:45 Flap retraction begins
5:39:55 Autopilot disengages
5:40:00 MCAS begins MCAS-ing

So, it was a minute and fifteen seconds between the initial indication of a failure, and the undesired, uncommanded trim input. During that time, the pilots did not execute a single step of the UAS NNC checklist that they should have been following from memory. But they sure spent a lot of time heads-down button-pushing that autopilot. It's clear that they were not comfortable manually flying the aircraft as the checklist requires. To be noted, until 5:40:00, the airplane would have been behaving exactly as an NG would during the same type of AOA vane failure, and the procedure to follow during UAS is identical.



1. Excerpt from Boeing FCOM Philosophy and Assumptions; “• the full use of all automated features (LNAV, VNAV, autoland, autopilot, and autothrottle). This does not preclude the possibility of manual flight for pilot proficiency where allowed” in other words become masters of automation.

2. “startle Factor” + prolonged confusion = Panic

3. Panic = return to comfort Zone.

4. Hence at 50’ LNAV selected and 400’ VNAV selected and Autopilot attempted, “HAL” will fix it.

5. What would that comfort zone be? Automation of course. That’s what the industry teaches.

6. Manual flight with a flight director ON does little to solve the issue, it must be flight director and autothrottle off to achieve the familiarity and thus comfort zone. Do we want pilots flying commercial jets as if in a Cessna 152? Catch 22.

Question

1. At 100’ what was the difference in IAS Left vs Right? Is it clear which is erroneous? Could your Trim sheet/ Load sheet be wrong?

2. At what timeline should they have identified UAS and not an approach to stall?

3. If UAS identified should they have powered back to 80% N1 and Pitch 10”?

4. How much does the stick shaker noise, vibration, low altitude and low time FO affect you, and when was the last time you trained for this?

5. Hundreds of hours and discussion on this thread and no consensus, but this flight lasted 6 minutes and was doomed by 3 minutes.

With what we know now, all on this thread could survive the same scenario, how about before?

Pilots are so trained to follow the memory items; it doesn’t allow them to fly on instinct in panic mode. Panic Mode starts with wings level, pitch and power and let the brain settle.

[Lost in Saigon]

There are two followup aspects to your question, depending on the version of MCAS 1.0 and MCAS 2.0:
- MCAS 1.0 was designed to satisfy the criteria that you describe, though not smoothly, due to the 5 second pause.
- MCAS 2.0 may remove the option of repeated trim during the same high AOA "event", depending on the definition of event. This would not satisfy the 25.173 criteria, if it allowed the pilots to do a second pull into the high AOA region, after interrupting MCAS by blipping the stabiliser trim switches.

Long ago I posted this assertion: It is logically impossible to design a system that satisfies both limited MCAS activation and 25.173 criteria simultaneously. One of the two limits has to be broken in some scenarios, for example pilots repeatedly entering the high AOA condition. I have not seen any evidence to contradict my assertion.

I think everyone is missing the the point of MCAS. MCAS is supposed to operate behind the scenes to add just a little nose down trim at high angles of attack to replicate the "feel" of a "normal" aircraft" as the pilot pulls the nose up WTHOUT TRIM. FAA 25.173 requires it for nose up, neutral trimmed high angles of attack. It is not needed if the flaps are out or if the autopilot is on. It is also not needed if the pilots decides to trim on his own.

When MCAS has been triggered at high angles of attack, as soon as the pilot touches the trim, MCAS is disabled because the pilot now has decided to trim for whatever trim feel they want. There is now no need for MCAS as there is no FAA mandated "feel" that needs to be demonstrated. MCAS does not operate for 5 full seconds after each application of trim.

So yes, I believe MCAS can satisfy both limited activation and 25.173 criteria simultaneously.

[Sublogic]

The Max crashes might have to do with pilots shortcomings but never with the airline, country or origin. Af447 made this clear once and for all.

[wonkazoo]

Can anyone here definitively state what Reg MCAS was intended to provide compliance with??

I have seen several different sources cite to 14CFR 25.203 "Stall Characteristics" ("No abnormal nose-up pitching may occur.") and others to 14CFR 25.173(c) Static Longitudinal Stability (The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.)

I'm working on something and it would be immensely helpful to have a factual basis for the certification requirements that MCAS was intended to provide compliance with. This is actually somewhat of a big deal- I had been working off the predicate that it was for "increasing feel" approaching high alpha, but I see now with either of those Regs that might not be correct.

Whatever the reg is that MCAS was implemented for it seems clear that the system as designed is not a feel enhancement, it is a flight control system, which raises a huge number of questions if you think about it for too long...

Thank you in advance for your time and for passing on any relevant information-
dce

[safetypee]

sadtraveller, https://www.pprune.org/showpost.php?p=10460680&postcount=4708
A few quibbles, but I won’t.
A ‘factual’ review, credible of a determined safety case to improve our industry.

Opinion. Recall that “opinion is really the lowest form of human knowledge. It requires no accountability, no understanding.” (B. Bullard) Yet your views provide the very necessary grounding for logical reappraisal, which at this stage of the thread has been lacking.

[Cows getting bigger]

Wonkazoo, I don’t have an answer to your direct question but erring towards flight control systems, I think that 25.672 is also relevant.

[Lost in Saigon]

Can anyone here definitively state what Reg MCAS was intended to provide compliance with??



I have never seen any official reference to the actual FAA requirement.

This is the most detailed explanation I have seen: 737 MAX Maneuvering Characteristics Augmentation System (MCAS) (http://www.b737.org.uk/mcas.htm)

MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation.

The LEAP engine (http://www.b737.org.uk/powerplant.htm#LEAP) nacelles are larger and had to be mounted slightly higher and further forward from the previous NG CFM56-7 (http://www.b737.org.uk/powerplant.htm#CFM567BE) engines to give the necessary ground clearance. This new location and larger size of nacelle cause the vortex flow off the nacelle body to produce lift at high AoA. As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics". Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. MCAS was therefore introduced to give an automatic nose down stabilizer input during elevated AoA when flaps are up.

[PEI_3721]

Yo gums,
‘We need some test community inputs to this discussion.’

Not sure how any further input from the test community or any other could contribute.
A distant, philosophical view is that with hindsight people view situations as they wish, based on knowledge (often inaccurate) and (irrelevant) past experiences, then fit these to interpretations of incomplete information - a narrow window from FDR and CVR, together with the hazard of ‘internet’ belief (social media).
We rarely question our own thoughts.
This might be the greater threat to the industry than any technical malfunction if these aspects relate to all flight crews (no reason why not - just being human).

Whilst it is unreasonable to expect everyone to have deep knowledge of CS/FAR 25 etc, there should be general confidence that most, if not all aspects of design, certification, and testing have been considered. Rarely and unfortunately in this instance, these processes are not without mistake; similar to the ‘mistakes’ observed in operation. These do not warrant blame, and rarely can ‘cause’ be identified, which would be meaningless anyway - a social construct.

Experiences from investigation of serious incidents (non fatal), with the benefit of pilot interview, conclude that humans behave rationally according to how they saw the situation at that time (irrational with hindsight to an external observer).
Subsequent review of the FDR enable crews to re-evaluate their understanding, not changing what they did, nor providing understanding of why they acted as they did (they don’t know - don’t recall why), but significantly they are able to realign time frames (wildly misjudged), and the event order according to individual viewpoint (no such thing as a shared mental model).
Thus after the event, there is no way of being sure that any discussion represents anything relevant to crew thought, analysis, belief, and action; even accident reports.

A way forward is to consider what can be learnt from these accidents; of course including the comments above, but where speculation - what if - is a basis for safety improvement. Irrespective of any relevance to these accidents, because they will not occur in exactly the same way again.

Test community input; might readjust the views on the crew’s contribution in minimising the effects of malfunction, particularly with ‘grandfather rights’ aircraft. We are not as good as we think we are.
For the future, be very concerned about the balance between new design (or modification) and pilot ability; technology advances faster than crew training / adaptation.
Human performance will limit the advance of technology; but technology will further erode the human role because of lower cost.

[dingy737]

Agreed! and they think the MAX will fly anytime soon? if their are bookies taking bets let me know how to contact them.

[gums]

Salute!

Thanks, PEI. I was and am still looking for the aero explanation that is more relevant than basic control column feel.

Unless you are flying a Mk 1, Mod 1. version 737, you need to try the new suckers. The plane is not the one your grandfather flew.

"Lost" quoted the British dot org explanation, and that that is one that I support most of all.

Gums sends...

[Icarus2001]

As far as I know it has not been conclusively reported, but it appears that based on the trim traces that MCAS is in fact capable of overriding thumb trim and not the other way around, despite claims to the contrary. Completely wrong.
See the Boeing bulletin posted above, trim use will always override MCAS.

[Loose rivets]

Lost in Saigon #4673

It has been said time and time again: MCAS is not for stall protection.

Yes, thank you. After reading what is probably nearer 6,000 posts, and many other articles, I think I've got the hang of what MCAS is, or is supposed to be.

*********

Having just read the AV H article in the parallel thread, I posted on some of the issues, and implied the impossibility of average crews comprehending the BackUp switch circuitry after a quick read in. If the AV H's questioner's knowledge is correct, things are very, very different to the concept of two switches simply being in series.

I also mentioned one of my main bee's in bonnets. The second (underfloor) column switch - which may or may not be there, and if it is, allowed to function at all times. In the same question, they made an eye-opening statement about the switch function. It's going to take time to absorb the circuitry at the bottom of the article, but again, it's not as straight forward as I'd thought.

Crash: Ethiopian B38M near Bishoftu on Mar 10th 2019, impacted terrain after departure (http://avherald.com/h?article=4c534c4a/0052&opt=0)

The posting, again, of the old out-sourced fabrication issue a few posts back. Could this be connected, though some time after the associated whistle-blowing.

14 - Russia's MAK revoked the certificate of airworthiness for the entire 737 family (from 737-100 to 737-900) three years ago claiming they found an issue in the pitch/altitude control system of the aircraft (suggesting that at least the Tatarstan crash in Kazan as well as the Flydubai crash in Rostov may have been the result of that weakness) but did not receive a satisfactory response by the FAA and Boeing, also see News: Russia suspends airworthiness certification for Boeing 737s, but does not prohibit operation of 737s (http://avherald.com/h?article=48ee3567). What was the issue they found?

[737 Driver]

Having just read the AV H article in the parallel thread, I posted on some of the issues, and implied the impossibility of average crews comprehending the BackUp switch circuitry after a quick read in. If the AV H's questioner's knowledge is correct, things are very, very different to the concept of two switches simply being in series.

.

I have no doubt that this is true, but it is also largely irrelevant from a procedural viewpoint. The pilots don’t need to be able to read a wiring diagram and tell you all the things that happens when they throw the cutout switches. They just need to know when they need to throw the cutout switches - as in the case of the runaway stab trim procedure.

[PaxBritannica]

Conclusion:

In my opinion, Boeing has acted disgracefully in this situation and should be prosecuted criminally for manslaughter (perhaps this is an opportunity for Barr to prove that he is not a Trump stooge). Meanwhile the FAA has been completely compromised and corrupted by the kleptocracy that is taking over America. These are systemic failings rather than a one-off incident, and they raise the question of how many other similar failures remain lurking in the shadows due to negligent management practices and oversight in a country that is rapidly losing any respect for the rule of law. No outcome short of a complete (and transparent) overhaul of Boeing's safety culture, prosecution and incarceration of senior management, and possibly even a break-up of the company (e.g. splitting off commercial aviation from defense) will make me comfortable flying on any recently-produced Boeing metal. I'll be putting my money where my mouth is by exclusively booking Airbus until these changes are made. I'm not holding my breath, so it looks like I'll be flying Airbus for some time to come.

sadtraveller Thank you for this neat summation of the facts. As a fellow frequent flyer, I'm with you in wanting a safe flight despite non-optimal staffing in the front seats.

I'd also question the focus on MCAS alone. Boeing did not react to Lion Air as if a known risky design choice had been exposed. My own impression was that MCAS hadn't been on their minds, and they were surprised and slightly irritated that it had caused problems. Ergo, I assume that the MCAS design was of a piece with their general design standard. If this is the case, it's reasonable to think that there may be more potential bear-traps in the MAX design. Are there any other systems dependent on a single sensor? Are there any other silently disabled features that Boeing haven't mentioned? Can any other flight characteristics be affected by features undisclosed to the pilot?

If I were an aviation authority, I'd want those questions answered. It's a shame the FAA isn't leading the way.

[MurphyWasRight]

Originally Posted by Loose rivets https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-237.html#post10460962)
Having just read the AV H article in the parallel thread, I posted on some of the issues, and implied the impossibility of average crews comprehending the BackUp switch circuitry after a quick read in. If the AV H's questioner's knowledge is correct, things are very, very different to the concept of two switches simply being in series.
.
I have no doubt that this is true, but it is also largely irrelevant from a procedural viewpoint. The pilots don’t need to be able to read a wiring diagram and tell you all the things that happens when they throw the cutout switches. They just need to know when they need to throw the cutout switches - as in the case of the runaway stab trim procedure.

Unfortunately the AV herald "question" referenced above commingled the under floor cutout switches with the 2 center 'stab cutout' switches. If carefully parsed it might be correct but very hard to read.
Here are the relevant facts on the cutout switches:

The 737 NG the cutout switches:
left cutout kills all electric trim (protects against stuck pilot switches as well as some faults in motor module)
right disable automatic trim only.

On the 737 MAX either cutout switch disables all electric trim.
The 28V power to the main trim motor 115V 3 phase relay is in series through both switches. The av herald shows some function not identified secondary contacts that are probably status inputs to other systems.

The 737 MAX labels were changed to 'primary and 'backup', the changed functionality was not mentioned in at least some version of the 'i-pad conversion course.

One theory is that the ET pilots used the right switch and then discovered they had no manual electric trim, which they would have had on NG.

Others have posted that the runaway trim procedure was changed from first using the right switch only to using both a few years ago for unknown reasons.
No one has posted a rational sounding reason why the switch functions were changed.

[Loose rivets]

Originally Posted by Loose rivets https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-237.html#post10460962)
Having just read the AV H article in the parallel thread, I posted on some of the issues, and implied the impossibility of average crews comprehending the BackUp switch circuitry after a quick read in. If the AV H's questioner's knowledge is correct, things are very, very different to the concept of two switches simply being in series.

.


737 Driver #4736
I have no doubt that this is true, but it is also largely irrelevant from a procedural viewpoint. The pilots don’t need to be able to read a wiring diagram and tell you all the things that happens when they throw the cutout switches. They just need to know when they need to throw the cutout switches - as in the case of the runaway stab trim procedure.


I know, and I concede I've always been a 'know every nut and relay' kind of bloke. But this, if true, means the function of the BU switch is much more subtle than I'd realised.

My first reaction was of curiosity, wondering where that would take us. It seemed to imply only throwing the RH switch might be significant.

However, it'll be 03 Sparrows again before I get my head down - about par for the course since November. I'll look at the AV H's list and circuits again tomorrow as I usually have a photographic memory for systems, but these logic changes are leaving me in a fog. Don't like it. Hope it's not age related!!

[737 Driver]

The 737 NG the cutout switches:
left cutout kills all electric trim (protects against stuck pilot switches as well as some faults in motor module)
right disable automatic trim only.

<snip.

Others have posted that the runaway trim procedure was changed from first using the right switch only to using both a few years ago for unknown reasons.
No one has posted a rational sounding reason why the switch functions were changed.

Small correction. On the NG, the left switch disables the main electric (pilot actuated) trim and the right switch disable all automatic inputs (Speed Trim/Mach Trim/Autopilot Trim). We used to try to identify the offending system and actuate these switches separately in the runaway stab trim procedure depending on the situation. Somewhere along the way, Boeing changed their philosophy on the procedure (probably part of a larger trend of moving away from “troubleshooting” type actions) and now we always use both switches when necessary. I have previously speculated that two switches were retained in the MAX for both redundancy against possible relay welding and to simply harmonize the procedural aspects of runaway trim between the NG and the MAX. That is, both aircraft have two switches (for different reasons) and you always use both switches at the same time.

[kiwi grey]

[snip]

18. (Opinion) If there are regions of the 737 flight envelope (e.g. extreme trim, opposing elevator) under which pilots lose vertical authority, the whole 737 fleet, both maxs and NGs (assuming that they are also affected by the same issue), should be grounded until such a time as trim deflection is mechanically limited to prevent entry into these uncontrollable regions of the flight envelope.

[snip]


This
My reading of this whole catastrophe is that the certification of the B737MAX and the B737NG may now be thrown into question.

The FAA will undoubtedly approve "MCAS 2.0" in as quick a time as they consider respectable, but the evidence shows that there is such a degree of regulator capture that this will be hard to see as an objective evidence-based process.
Others, particularly CAAC and EASA, may not be so easily convinced. The Russian regulator would probably be onside with that judging by their actions a couple of years ago to attempt remove certification from the B737NG.

That would be catastrophic for Boeing and for the air transport industry world-wide: half the global narrow-body fleet grounded indefinitely hardly bears thinking about.

[neville_nobody]

My reading of this whole catastrophe is that the certification of the B737MAX and the B737NG may now be thrown into question.

The FAA will undoubtedly approve "MCAS 2.0" in as quick a time as they consider respectable, but the evidence shows that there is such a degree of regulator capture that this will be hard to see as an objective evidence-based process.
Others, particularly CAAC and EASA, may not be so easily convinced. The Russian regulator would probably be onside with that judging by their actions a couple of years ago to attempt remove certification from the B737NG.

I think the Whistle blower testimony may impact what decision that the FAA is even able to make. I'll bet that both Boeing and the FAA are keen to just patch MCAS and move on.
However if they start getting expert whistle blower testimony that brings in to question the whole certification process of MCAS and the reasons for its existence the FAA will be out of options other than some sort of re certification process which is a whole new can of worms.

[Snyggapa]

To be honest I would be fairly confident that given the amount of scrutiny that the redesigned MCAS has, it would be "safe enough".

What concerns me would be any other, as yet unknown/undisclosed "features" that are lurking in the background that haven't yet been disclosed because they haven't yet contributed to a smoking hole in the ground - essentially have any other corners been cut or sub-optimal design or engineering decisions been made. I would hope that this is what the FAA and other regulators are scrutinising right now.

I would also be fascinated if a gap analysis has been done between the MAX and what would need to change, were it a new aircraft type being certified today - several people have commented that "it would never be certified today" and "it relies on grandfather certification" - so in what ways does the MAX come up short to today's expected regulations?

[yanrair]

What a truly superb analysis. I suspect this could very well be plaigerised in its entirety and feature in various court cases in the future.

Regards

I think Alchad that you would have to say that only a few of the Comments 1-33 are accurate and even then, were not the cause of the crashes. Only factors leading to the events. I will look at the 33 comments as will others and I am sure they will be examined one by one for accuracy, relevancy and bias. I look forward to that input from others wiser than I.
Happy flying
ps - would fly on a Max today if I could fine one going somewhere, provided the pilot had been trained in multiple error warnings and knew his pitch and power settings for each phase of flight. The airlines I fly on do that. Someone said today "are we going back to the Cessna 152?" Well, the 737 is a large 152 and that is its beauty in my view. It flies with very little working except it needs the engines, and even without them, has made many safe landings. But, the pilots HAVE to know how to fly. The 737 is not an Xbox. But then nor is an A330 as we saw in the AF 447 crash where the pilots had no idea what was happening to them.
We are not going to get away from the issue of world wide movement towards minimalist training supplemented by smarter and smarter avionics which can save the pilots from their own errors. An old but not bold pilot.
Y

[Loose rivets]

737 Driver

. . . On the NG, the left switch disables the main electric (pilot actuated) trim and the right switch disable all automatic inputs (Speed Trim/Mach Trim/Autopilot Trim). We used to try to identify the offending system and actuate these switches separately in the runaway stab trim procedure depending on the situation. Somewhere along the way, Boeing changed their philosophy on the procedure (probably part of a larger trend of moving away from “troubleshooting” type actions) and now we always use both switches when necessary. I have previously speculated that two switches were retained in the MAX for both redundancy against possible relay welding and to simply harmonize the procedural aspects of runaway trim between the NG and the MAX. That is, both aircraft have two switches (for different reasons) and you always use both switches at the same time.

This is a very revealing quote. I can see how the procedures evolve, or de-evolve. But I can also see how it could lead even attentive crews down a very dark garden path.

#845 on the parallel thread

we have promise of a further probing into the AV H's list and circuits. I haven't woken up yet.

737 Driver's comments about the need to know levels I concede completely though as I say, if I were young . . .


FrequentSLF #843 on parallel thread. Quote:I am not a pilot, but I have eletrical and automation background.
Based on the wirings that are available on the net the systems are as stated.
MCAS is not stopped by column switches!
MCAS cannot be disabled without cutting off manual electrical trim, which means only wheel cranking can be used if CUT OFF switches are used.
CUT OFF switches are connected in series, and renamed PRI and B/U, either one will CUTOFF all electrical controls (manual thumb on control column, autopilot, STS, MCAS), while on NG one switch will cut off automatic trim, while the other whole cut off the electrics.
Well, I found it hard to reconcile the MAX system as described in the AV H's question list - with the outline wiring we'd all been lead to believe was simply a series BackUp configuration. It was too late last night to trace circuits, but 737 Driver did protest it doesn't matter about the details, as long as the crew take the right actions. I have never thought like that and if I'd been on type, (and 40 years younger) I would have known exactly what that circuit did. At least, I hope I would, given I'd got the first clue that something like MCAS was lurking in the background. But then, I'd spent sproghood on the electronics workbench.

Now to another issue in the Herald's list. They go back to the black box taking in good AoA data and corrupting it - in both if not all, cases. Certainly, the chance failure of three vanes stretches the old credulity, though the balance weight hypothesis in the ET flight is very compelling. But along a pure logic line, I would have looked very carefully at the prior reports - in addition to the three major vane issues. The more I read the more I'm not satisfied the Herald's suggestion is not correct. It leaves me with a deep concern about what I've described as a ghost in the machine.

Apart from the digital errors fitting nicely with the three vane positions - they take the very rapid change of angle as being more electronic than a pendulous swing. But as I say, the latter is good fault modelling. It's just that slight angle change from a long steady error state, to a slightly different long steady state. That's odd.

[MurphyWasRight]

Now to another issue in the Herald's list. They go back to the black box taking in good AoA data and corrupting it - in both if not all, cases. Certainly, the chance failure of three vanes stretches the old credulity, though the balance weight hypothesis in the ET flight is very compelling. But along a pure logic line, I would have looked very carefully at the prior reports - in addition to the three major vane issues. The more I read the more I'm not satisfied the Herald's suggestion is not correct. It leaves me with a deep concern about what I've described as a ghost in the machine.

Apart from the digital errors fitting nicely with the three vane positions - they take the very rapid change of angle as being more electronic than a pendulous swing. But as I say, the latter is good fault modelling. It's just that slight angle change from a long steady error state, to a slightly different long steady state. That's odd.
There were not 3 separate 3 AoA issues, the last 2 Lion Air flights had the same AoA sensor with exact same offset. The AoA sensor had been replaced before as a troubleshooting measure but we still have no facts on the returned units condition.
As to the slight change in steady state in ET trace:
The first significant) downward bump in vertical G was at 05:41:15 coincident with the change. Assuming the AoA (sans vane) sensor was wedged at a limit (bird innards even) it was jostled and settled slightly lower.

I don't really understand the drive to make both instances have the same cause since the traces are totally different.

Both Lion air flights had an active AoA with a fixed offset. This 'might' be electronics but could also be explained by a mechanical issue.

ET had a sudden swing to full scale and then tracked G at the end. The speed of the initial swing is hard to read from the graph but does not look faster than the random variations on the working unit.

[MurphyWasRight]

737 Driver

Quote:
. . . On the NG, the left switch disables the main electric (pilot actuated) trim and the right switch disable all automatic inputs (Speed Trim/Mach Trim/Autopilot Trim). We used to try to identify the offending system and actuate these switches separately in the runaway stab trim procedure depending on the situation. Somewhere along the way, Boeing changed their philosophy on the procedure (probably part of a larger trend of moving away from “troubleshooting” type actions) and now we always use both switches when necessary. I have previously speculated that two switches were retained in the MAX for both redundancy against possible relay welding and to simply harmonize the procedural aspects of runaway trim between the NG and the MAX. That is, both aircraft have two switches (for different reasons) and you always use both switches at the same time.

This is a very revealing quote. I can see how the procedures evolve, or de-evolve. But I can also see how it could lead even attentive crews down a very dark garden path.


This could be a case of compounded unexamined assumptions along the way:

The initial 737NG safety analysis used the availability of separate cutouts (automation and all) to justify smaller wheel/harder to move under high loading since in most cases pilot electrical trim would still be available.
This may also have been a factor in dropping training on the 'unloading' technique.

Over time training was simplified, not by itself a bad thing, but did not take the above into account.

When MAX was designed the fact that training always used both switches was used to justify removing the seperate functions for whatever reason.

Some have suggested that the training was changed to accomodate the upcoming MAX, I highly doubt this was true since there was no technical need to change the functionality to add MCAS.

[meleagertoo]

Others have posted that the runaway trim procedure was changed from first using the right switch only to using both a few years ago for unknown reasons.
No one has posted a rational sounding reason why the switch functions were changed.
I did my 737-3/400 initial course in 1998 and have no recollection at all of ever using just one of STAB TRIM CUTOUT switches. They were always, unless seniity has completely overtaken me, used together. Seems rather more than 'a few years ago' to me.

[wheelsright]

:



Alll 3 of the FDR traces clearly show MCAS kicking in ~5 seconds after the last manual electric trim.

It is not clear what the current published FDR traces are actually reporting... I am not saying that your interpretation is wrong but it is not absolutely certain. Does the thumb switch have absolute authority in all circumstances (save for when electric trim is disabled)? The wiring schematics available suggests otherwise and the detailed software logic is not publicly known. The FDR data is not clear whether it is reporting inputs or final outputs or something in between. I have read what is available in this thread and still have doubts that there is sufficient information to be sure. What is certain is that the MCAS system was not properly or adequately designed. It is inherently dangerous and should never have been approved. Whether the pilots should or could be expected to resolve the defective system is a secondary issue. It is simply unacceptable for a critical system to continue to rely on plainly unreliable sensor information. The common factor is unreliable AoA that is easily detected but the system ignores. Autopilot is disabled but why on earth is MCAS allowed to continue to operate?

[yanrair]

I did my 737-3/400 initial course in 1998 and have no recollection at all of ever using just one of STAB TRIM CUTOUT switches. They were always, unless seniity has completely overtaken me, used together. Seems rather more than 'a few years ago' to me.

No you are not going senile. Only a couple of year ago I was looking at training 737 pilots and they do what is says in the QRH - SWITCHES OFF. PLURAL. And they trained for multiple failures during loss of airspeed concurrent with stick shakers.
I had a discussion in that I suggested pulling the CB for the stick shakers once you knew it was a false warning but the answer was that "Boeing doesn't say that in the checklist". I would call that action airmanship though!
Cheers
Y

[aterpster]

I did my 737-3/400 initial course in 1998 and have no recollection at all of ever using just one of STAB TRIM CUTOUT switches. They were always, unless seniity has completely overtaken me, used together. Seems rather more than 'a few years ago' to me.
We always used both switches on the 707 and 727, circa 1964-83.

[MurphyWasRight]

Originally Posted by meleagertoo https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa-238.html#post10461266)
I did my 737-3/400 initial course in 1998 and have no recollection at all of ever using just one of STAB TRIM CUTOUT switches. They were always, unless seniity has completely overtaken me, used together. Seems rather more than 'a few years ago' to me.
No you are not going senile. Only a couple of year ago I was looking at training 737 pilots and they do what is says in the QRH - SWITCHES OFF. PLURAL. And they trained for multiple failures during loss of airspeed concurrent with stick shakers.
I had a discussion in that I suggested pulling the CB for the stick shakers once you knew it was a false warning but the answer was that "Boeing doesn't say that in the checklist". I would call that action airmanship though!
Cheers

Thanks all, interesting that it has been that way for many years,

Would take a while to find the post I was referring too, doesn't really matter though; as the total number of years increases sense of elapsed time does seem to compress.

This does totally put to bed any idea that training was changed to accomodate MAX.

[SystemsNerd]

​​​​​​
[...]

Every time you say 'just fly the plane' or 'basic airmanship' or 'get another career' you're completely ignoring human factors. This is as dangerous as not knowing how to fly the aircraft. And this is why you're getting such a deservedly robust response from others on here.

Not ignoring the human element at all.

[...]

With respect, I think there may be a breakdown in communication here that may be in large part responsible for the ongoing disagreement. When people say "human factors", they don't mean "the human element", they mean Human Factors*, i.e., the study of how the human mind and body interacts with designed systems.

The human mind does not, ironically, work in the ways most people think it does - it has well-documented limitations and sources of error plumbed into its design. A human factors expert can I believe pretty trivially design a scenario where most (if not all) humans will consistently fail to correctly solve even relatively trivial problems, regardless of their competence under normal conditions.

Thus, when asking "why didn't they just fly the plane?", one possible answer is undoubtedly some variant on "they were incompetent". But another possible answer is "they were put into a scenario in which any human being would consistently fail to solve the problem, regardless of competence". Probably the truth is somewhere between those two points.

*See Wikipedia article "Human factors and ergonomics"

[737 Driver]

Thanks all, interesting that it has been that way for many years,

Would take a while to find the post I was referring too, doesn't really matter though; as the total number of years increases sense of elapsed time does seem to compress.

This does totally put to bed any idea that training was changed to accomodate MAX.

It was probably mine. At one time, my airline customized a number of procedures (in coordination with Boeing, mind you), so that may explain the difference. I’m pretty sure that all of our non-normals are now straight out of the Boeing manual.

[PEI_3721]

Yo gums,
‘… still looking for the aero explanation that is more relevant than basic control column feel.’
https://www.pprune.org/showpost.php?p=10460667&postcount=4706 (https://www.pprune.org/showpost.php?p=10460667&amp;postcount=4706)
https://www.pprune.org/showpost.php?p=10460941&postcount=4733 (https://www.pprune.org/showpost.php?p=10460941&amp;postcount=4733)

Nothing more specific to add; no detailed knowledge or reasoning in the public domain.
I suspect that the aerodynamic issue caught Boeing by surprise - late in flight testing; the existence or extent of change of pitching moment (stick force stability), its origin - engine nacelle, nacelle / wing interaction. Possibly a judgement that the handling characteristics would be ‘good enough’ - FAA association.

The need for modification - increased stick force to meet stability requirements at a few specific points in the flight envelope could be achieved with a range alternative approaches; hardware fixes - cf Mach trim, STS, feel shift. These progressively require ‘controlling’ parameters best achieved with software, thence use of ‘full’ software, but it wasn’t ‘full’ or comprehensively protected - faster, better, cheaper; NASA got that wrong; how we fail to learn, how quickly we forget.

The comparisons with modern FBY wire systems and the aerodynamics of those aircraft, adds little to this debate. The 737 airframe and systems design are very old, progressively enhanced, adapted to market demand - with the perception of new shiny technologies are better, at least cheaper.
A more suitable comparison would be with the 707 / 727; in my case the Comet. I recall that the Comet, or its derivatives had a ‘pitch gear change’, (not a manual shift), a smooth electrical repositioning of a mechanical cam which changed the ratio of stick to elevator (also used in the Sea Vixen to cope with transonic trim change). The need for Mach trim in commercial aircraft emerged as speeds increased (stability, stick force reversal), but due to its novelty, solutions were carefully thought through with reliable implementation.

The recent events will go down in history. History, as with war crimes, is written by the victors (lawyers, politicians).
The most important aspect for the industry is in what we learn, how this is to be learnt and implemented. The issues with certification processes may dominate - how to certificate modern systems, common standards, international approval, … trust.
The industry is transitioning from the generally knowable, to more uncertainty. How do we manage aircraft and people in an uncertain world.
https://www.farnamstreetblog.com/2013/11/decisions-under-uncertainty/ (Three parts linked)

FAA / Boeing could reconsider their relationship with ICAO, aviation language, safety culture.
More Integration opposed to dominating Assimilation:- https://www.dropbox.com/s/7425e8yykgkxpi3/Dominant%20and%20minority%20culture%20%2B.pdf?dl=0 (use website option)

[wheelsright]

The direction of this thread is difficult to understand. There seems to be a surprising focus on the cut-out switches but no rational explanation for the changes in the MAX series. If there are no circumstances that only one cut-out should be operated there, is clearly no point in having two cut-out switches. If two contacts are needed to be operated it could be mechanically interlocked into one lever. The current information suggest the two switches are a product of muddled thinking... hardly a confidence builder.

Purely speculating, the reason that MCAS is not automatically disabled in the event of conflicting sensor inputs may be because MCAS needed to be permanently active to comply with 14CFR §25.203(a) "Stall characteristics". However, it is difficult to believe that the designers could have considered it a better option to leave it to the pilots to disable MCAS rather than by the automatic system that would be immediately aware of AoA sensor malfunction. It seems to be possible that focus was on conforming to wording of regulations rather than designing an adequate system.

A critical system that is intended to work in all circumstance must be designed in a way that reduces risks of malfunction to an acceptable level. Reliance on a single sensor or system does not appear to satisfy this obvious requirement. In the event that a critical sensor is no longer reliable, the system must automatically fall back to an alternate. That could be an alternate duplicate system or the manual control of the pilot or a combination or several nested fall-back options. The evidence so far is quite clear that Boeing failed to properly consider these options and required pilot intervention on scant information. In my view, it was negligent design and I suspect that I am not alone.

Many of the comments on this thread focus on the failure of the pilots to resolve the situation. There is good evidence that if the captain had handed control to the right hand seat or used the cut-outs earlier that they would have been successful. However, it does not excuse the fundamental design defects. In actual fact, Boeing could have easily prevented any uncertainty created by unreliable AoA through additional training automation and notification. There is no excuse for the design defects.

Further, much has been made of additional pilot training or improved memory items, QRH etc. Unfortunately, it is trying to close the stable door after the horse has bolted. The existing MCAS system will never be used again and any training or manuals will be based on a substantially different systems. Really all the focus at this stage must be on correcting the design defects... any manuals and training will fall from the new systems and will hopefully learn from the inadequacy of the previous systems and training.

I look forward to learning exactly how the MCAS electric trim system worked and how the situation will be resolved. One of the issues that I would like to further understand is why the pilots only appeared to make shortly electric trim corrections when it seemed likely that they would be trying to make large corrections. The FDR trace combines MCAS and electric trim... it is therefore uncertain what the thumb switch position was in.

Would permanently holding the thumb switch for nose-up, override AND from MCAS? Does MCAS cyclically override the thumb switch input in the 10s 5s cycle that requires further release and activation of the thumb switch. ie is the Boeing Ops Manual Bulletin TBC-19 entirely accurate... namely:

In the event of erroneous AOA data, the pitch trim system can trim the stabilizer
nose down in increments lasting up to 10 seconds. The nose down stabilizer trim
movement can be stopped and reversed with the use of the electric stabilizer trim
switches but may restart 5 seconds after the electric stabilizer trim switches are
released.

If this is true then it would be possible (not desirable) to use electric trim to override MCAS without using the cutout switches. MCAS could be interrupted and corrected every time it kicked in. I suspect it is not entirely accurate... I wonder if anyone has an authoritative answer? None of this excuses MCAS remaining active with unreliable AoA information.

[slacktide]

I would also be fascinated if a gap analysis has been done between the MAX and what would need to change, were it a new aircraft type being certified today - several people have commented that "it would never be certified today" and "it relies on grandfather certification" - so in what ways does the MAX come up short to today's expected regulations?

Fair questions. The relevant regulations are generally referred to as the "Changed Product Rule", and are documented in 14 CFR part 21.101 and 21.19. FAA Advisory Circular 21.101-18 provides guidance on how to interpret and apply the regulations, including how to perform a gap analysis to compare the previous regulation to the new regulation. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_21.101-1B.pdf (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_21.101-1B.pdf) The general takeaway is the changed systems, and affected systems that are unchanged but impacted by change, must generally step-up and comply with the most recent regulations.

The certification basis of an aircraft is a list of which regulations it has been demonstrated to comply with, and at which amendment level of that particular regulation is being used to show compliance. The certification basis is agreed to by the manufacturer and the FAA at the beginning of the certification process. The manufacturer has 5 years to complete certification of the aircraft, and the manufacturer is not required to comply with regulations that are changed within that 5 year period.

The cert basis is documented in the Type Certificate Data Sheet. Here's the 737 TCDS, the MAX 8 is on page 71. http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/179cdacd213801658625832a006b2e37/$FILE/A16WE_Rev_64.pdf

For each regulation, the center column lists the amendment level that the airplane complies with. NA indicates "No Amendment."

Then, you can go to the CFR and compare the most current amendment level to the amendment level in the TCDS. https://www.govinfo.gov/content/pkg/CFR-2018-title14-vol1/pdf/CFR-2018-title14-vol1.pdf

For example, the MAX complies with 25.107 amendment 135 for Takeoff Speed, and that is the current amendment level in the CFR.

Another example, go in the TCDS and look at 25.807 for emergency exits. For some of the doors, the MAX complies with the most current amendment level 114. For others, it complies with amt. 72. Additionally, they are compliant with 25.807(c)(3) at amt. 15, because this section was removed from newer versions of the regulation.

[ams6110]

Would permanently holding the thumb switch for nose-up, override AND from MCAS?


Yes, but you certainly would not want to do that, as if you literally held the switch up "permanently" you'd end up at the maximum ANU trim configuration.


... would be possible (not desirable) to use electric trim to override MCAS without using the cutout switches. MCAS could be interrupted and corrected every time it kicked in. I suspect it is not entirely accurate... I wonder if anyone has an authoritative answer? None of this excuses MCAS remaining active with unreliable AoA information.

Yes this is entirely possible, and is what happened on the penultimate flight of the Lion Air accident aircraft.

[rodlittle]

From something Ive just read MCAS was to compensate for the fact that due to the new engine nacelles the pitch stablity was so poor that it would tighten up in a turn at low airspeed and that it actually required a push on the control column to defeat this which is quite unaceptable in an airliner, not so much in a Pitts.
Obviously this could not have been corrected by adjusting the elevator cct feel so it explains the why of why did they do it this way

[bill fly]

From something Ive just read MCAS was to compensate for the fact that due to the new engine nacelles the pitch stablity was so poor that it would tighten up in a turn at low airspeed and that it actually required a push on the control column to defeat this which is quite unaceptable in an airliner, not so much in a Pitts.
Obviously this could not have been corrected by adjusting the elevator cct feel so it explains the why of why did they do it this way


Thats interesting Rod - what was is that you read?

[rodlittle]

a report in Pilot magazine by Bob Grimstead, cant comment on its accuracy but hes a reputable man

[Chronus]

It remains an inescapable fact, meaning as in the sense of a reality, that the introduction of a software based modification became a necessary in order to get this plane certified. That must have been considered as the most optimal solution to achieve the commercial aims of introducing a plane that could be competitive to others on the market, namely the Airbus offerings. The B737 had to be kept alive to do that. But how could it be possible to keep a plane designed half a century ago may still be fit for today`s world of aviation. The Douglas DC10 was also an all time winner, but can you imagine kitting it out with the latest high ratio by pass turbo fans of today, installing some fancy computers and software in it and saying here is the answer to short haul commuter, so long as you can get your pax to don their oxy masks if we hit some bad wx. Not really all that much different to saying the B737 MAX is more than safe as is, but just to make sure no airline has sat a pair of morons up front, we have with our clever MCAS thingy tell the computer how to handle them. Now if that does not make sense as to why they put in this MCAS thingy majig, then why did they do it in the first place. That of course takes us back to where we started, which then means we got nowhere and that is the whole purpose of the whole exercise.

[slacktide]

The Douglas DC10 was also an all time winner, but can you imagine kitting it out with the latest high ratio by pass turbo fans of today, installing some fancy computers and software in it and saying here is the answer to short haul commuter,

So, a MD-11?

[robocoder]

Thus, when asking "why didn't they just fly the plane?", one possible answer is undoubtedly some variant on "they were incompetent". But another possible answer is "they were put into a scenario in which any human being would consistently fail to solve the problem, regardless of competence". Probably the truth is somewhere between those two points.


​​​​​​Thank you so much for this This is why I cannot accept the analysis of those that pile with unwavering assertiveness on the pilots' performance. We have only a partial view of what they experienced. We simply cannot know what the average crew would do in their shoes, vs what some hypothetical post-hoc average response should be, as evident as it may seem. Even so, are they at fault for the training they received? That's why when someone can't come back to tell their version, I prefer unanswered questions to "sure" answers.

[wonkazoo]

From something Ive just read MCAS was to compensate for the fact that due to the new engine nacelles the pitch stablity was so poor that it would tighten up in a turn at low airspeed and that it actually required a push on the control column to defeat this which is quite unaceptable in an airliner, not so much in a Pitts.
Obviously this could not have been corrected by adjusting the elevator cct feel so it explains the why of why did they do it this way

This is a part of what I've been working on- where did you read that information??

Everyone has been focusing on the failure modes of MCAS and related components, but there has been little discussion about how stupidly huge the whacks that MCAS takes at a relatively minor (so we have been told) control feel issue. MCAS is, no two ways about it, a control system, one that exerts immense authority over the most important control surface on the airplane. Such a system, that sits unmonitored and unapologetically inserting itself when required, is unlikely to have been created in such a way without there being an equally significant issue that needed to be dealt with. Quickly and with huge control inputs.

THanks for sourcing that information-
dce

[wonkazoo]

Thus, when asking "why didn't they just fly the plane?", one possible answer is undoubtedly some variant on "they were incompetent". But another possible answer is "they were put into a scenario in which any human being would consistently fail to solve the problem, regardless of competence". Probably the truth is somewhere between those two points.

*See Wikipedia article "Human factors and ergonomics"

Thank you for breaking this down into such understandable terms. When I posted a number of days ago my own experience (extremely experienced pilot with proper training, well-rested and otherwise not prone to panic or loss of functionality) I was sharing this exact point: Despite the firm assurances of many here there are circumstances you can be placed into wherein you will cease to function effectively. No machismo or mantra is going to change your basic incapacitation and the time it takes for you to return to a quasi-functional human being. From the outcome of the two MAX flights it is abundantly clear that the crews were partially incapacitated and overwhelmed. Given that 6 out of 6 pilots who were in this situation (The earliest incident went on for six minutes until the GIB piped up and suggested the cutout the trim. That flight was also on the brink of total loss...) a 100 percent incapacitation rate argues fairly forcefully (and empirically) against the hero-pilot who will just FTFA.

Warm Regards,
dce

[david340r]

I have read the whole thread and I'm still a bit puzzled about the relative ability to trim electrically or manually. It's been asserted several times that the electric trim is more powerful than manual trimming, but we also have the checklist item "grasp and hold" if isolating electric trim doesn't control a runaway. This has been touched on earlier, but I can't envision a simple way that the manual trim wheels could win against the electric motor (stall it) whilst then not being able to actually trim over a wider range of conditions than the electric trim. Can anyone confirm there is some form of mechanism to achieve this and provide any information as to how it works?

I'm also wondering about the revisions to the stab trim motor unit over the years and what qualification tests are likely to have been required before revisions could enter into service. It appears the current motor is a brushless DC, but it seems extremely unlikely to me that it would have been this type of motor 50 years ago. It seems more likely to me that it would have originally been an a.c. motor running directly off the 3-phase supply. These can fairly easily be made multi-speed under relay control avoiding any control electronics and there are various design parameters that can be adjusted to control the speed/torque relationship, but perhaps it was some other type of motor. I wonder how accurately a modern brushless DC motor would reproduce the original characteristics, whatever type of motor it was, and whether this would have been flight tested over the full flight envelope before being signed off i.e. is it possible that not only the manual trim has changed in its authority due to reduced wheel size, but also the electrical trim capabilities may have changed in some subtle ways.

[yanrair]

[QUOTE=wheelsright;10461419]The direction of this thread is difficult to understand. There seems to be a surprising focus on the cut-out switches but no rational explanation for the changes in the MAX series. If there are no circumstances that only one cut-out should be operated there, is clearly no point in having two cut-out switches. If two contacts are needed to be operated it could be mechanically interlocked into one lever. The current information suggest the two switches are a product of muddled thinking... hardly a confidence builder.

Purely speculating, the reason that MCAS is not automatically disabled in the event of conflicting sensor inputs may be because MCAS needed to be permanently active to comply with 14CFR §25.203(a) "Stall characteristics". However, it is difficult to believe that the designers could have considered it a better option to leave it to the pilots to disable MCAS rather than by the automatic system that would be immediately aware of AoA sensor malfunction. It seems to be possible that focus was on conforming to wording of regulations rather than designing an adequate system.

A critical system that is intended to work in all circumstance must be designed in a way that reduces risks of malfunction to an acceptable level. Reliance on a single sensor or system does not appear to satisfy this obvious requirement. In the event that a critical sensor is no longer reliable, the system must automatically fall back to an alternate. That could be an alternate duplicate system or the manual control of the pilot or a combination or several nested fall-back options. The evidence so far is quite clear that Boeing failed to properly consider these options and required pilot intervention on scant information. In my view, it was negligent design and I suspect that I am not alone.

Many of the comments on this thread focus on the failure of the pilots to resolve the situation. There is good evidence that if the captain had handed control to the right hand seat or used the cut-outs earlier that they would have been successful. However, it does not excuse the fundamental design defects. In actual fact, Boeing could have easily prevented any uncertainty created by unreliable AoA through additional training automation and notification. There is no excuse for the design defects.

Further, much has been made of additional pilot training or improved memory items, QRH etc. Unfortunately, it is trying to close the stable door after the horse has bolted. The existing MCAS system will never be used again and any training or manuals will be based on a substantially different systems. Really all the focus at this stage must be on correcting the design defects... any manuals and training will fall from the new systems and will hopefully learn from the inadequacy of the previous systems and training.

I look forward to learning exactly how the MCAS electric trim system worked and how the situation will be resolved. One of the issues that I would like to further understand is why the pilots only appeared to make shortly electric trim corrections when it seemed likely that they would be trying to make large corrections. The FDR trace combines MCAS and electric trim... it is therefore uncertain what the thumb switch position was in.

Would permanently holding the thumb switch for nose-up, override AND from MCAS? Does MCAS cyclically override the thumb switch input in the 10s 5s cycle that requires further release and activation of the thumb switch. ie is the Boeing Ops Manual Bulletin TBC-19 entirely accurate... namely:

In the event of erroneous AOA data, the pitch trim system can trim the stabilizer
nose down in increments lasting up to 10 seconds. The nose down stabilizer trim
movement can be stopped and reversed with the use of the electric stabilizer trim
switches but may restart 5 seconds after the electric stabilizer trim switches are
released.

If this is true then it would be possible (not desirable) to use electric trim to override MCAS without using the cutout switches. MCAS could be interrupted and corrected every time it kicked in. I suspect it is not entirely accurate... I wonder if anyone has an authoritative answer? None of this excuses MCAS remaining active with unreliable AoA information.[/Q

Good explanation of MCAS story up to date
737 MAX - MCAS (http://www.b737.org.uk/mcas.htm)

[gums]

Salute!
@ david....

The diagrams of the trim motor and manual cable connection is over on the Lion crash thread.

Pretty clear that the cable will work no matter what unless it braks or tyhe motor/gear doofer freezes;

I'll let you do the research on thatother thread.

Gums suggests,,,,

[MurphyWasRight]

I have read the whole thread and I'm still a bit puzzled about the relative ability to trim electrically or manually. It's been asserted several times that the electric trim is more powerful than manual trimming, but we also have the checklist item "grasp and hold" if isolating electric trim doesn't control a runaway. This has been touched on earlier, but I can't envision a simple way that the manual trim wheels could win against the electric motor (stall it) whilst then not being able to actually trim over a wider range of conditions than the electric trim. Can anyone confirm there is some form of mechanism to achieve this and provide any information as to how it works?


My understanding is that the 'grasp and hold' would be for the case of failed brakes on the stab mechanism, it is a recirculating ball drive so can be back driven by aero loads
Manual wheel inputs actuates a clutch that disconnects the motor so you would not be driving or trying to stall it. (motor may be unclutched when not active as well).
Not sure of mechanics of that but easy enough to conceive of a 'tension in cable' mechanism that would actuate the disengage.

Whether my details are exactly correct does not matter much since the point is that one is not directly fighting the motor, just trying to move the stab.