teropa, the supposed problem which made this aircraft difficult to control was that the auto trim (AP engaged) continued to trim nose-up to maintain a stable condition. Although the AP was in GS mode, the trim state is a function of airspeed, thus as speed decreased – (pitch control attempts to follow the GS) more nose–up trim would be applied. The trim might not have reached maximum as there is usually a small delay, but the setting appears to have been beyond what would normally be expected during a go around resulting in large (out of trim) control force in the nose-up direction.
This is not to say that the aircraft would be uncontrollable, nor with the added nose-up moment from TOGA thrust; a critical issue is that the force appears to required a two-hand push in an erroneous situation where the thrust levers also require to be held forward due to the failure to disengage AT – retard mode still active due to an erroneous RA1.

Fred - no and yes.

Teropa - would you like me to post the initial Boeing MOM again (for the 5th time at least) or can you find that?

I suggest you also spend some of your Sunday wading through some of the 'BS' on the Airbus PGF thread too. There are some good answers to your question on trim there.

Analysis of OpenATC ADS-B Data
 

Warning: I realise the OpenATC ADS-B reported data is entirely unqualified so the following analysis must be read in this context.

The above flight data is presented at equal data point time intervals. By taking the recorded Latt/Long positions I have calculated the distance travelled between successive data points along the flight track. From this it is then possible to calculate the aircraft groundspeed for each 15 second time interval.

Unfortunately, I don't know how to insert the graphs into this post so a description of how would be appreciated!

Unitl then, I can describe that the graphs show the calculated speed tracking an average of 65 kts slower than the reported ground speed and reaching a minimum value of 130 kts calculated (203 kts reported) at 9 nm before the accident site then increasing to 183 kts calculated (191 kts reported) at 6 nm before the accident where the calculated speed then matches almost exactly the reported speed from then all the way to the accident site.

Simply taking the Starting & Accident Point data yields a track distance travelled of 26.66 nm in a time of 585 seconds (9 mins 45 secs) giving a calculated average aircraft ground speed of 158 kts which seems rather slow to me?

IF the reported Latt/Long points and time stamps are correct (a very, very big IF) then this would suggest the aircraft ground speed was considerably slower than would normally be expected and would suggest something else untoward was happening way before localiser and subsequent glide slope intercepts.

Let me know how and I'd be pleased to publish the graphs.

PPL&Eng

I would certainly NOT advocate hitting TOGA in a low level stall! Nor do Boeing.

PPL& - and other ADS-B'ers -appreciate the effort, but I really do not have much faith in this ADS-B thing as far as useful and reliable data is concerned. The FDR will have all the necessary info and tell the investigation if anything else went awry.

Many thanks to Johngreen for proof reading:)

RAlt.
 

Strange airplane: Dont have radio altímeter comparator light. Neither a Test sw

I feel another wig order coming on.......................'Seconds out! Round Three'

Pilots who allegedly have practiced recovery slow and in landing config describe a different picture (wrestling the column forward with both hands).

Fred Bound

They were on a Single Channel approach, no automatic GA available. And since TOGA seems to have been left alone, either the A/P untimely disengaged by itself or they disengaged it using one of the available methods: in this case it could have been pushing the column and trimming forward.

BOAC
Thanks.

Rainboe
No, I don't think it's easy. Nor do I expect that designing an aircraft to land itself is easy - but that was done 40 years ago and is considered normal now.

It's just that if the thrust/pitch couple, that has been mentioned dozens of times on here, is an expected result of the application of full or nearly full thrust, it is not unreasonable to expect that a modern aircraft control system might take it into account.

I'm not suggesting that TOGA was used here - just a question regarding the trim issue.

question: On the NG does the AP automatically disconnect at stick shaker?

Fred - can I ask you to try and sift through this thread as well? The a/c is easily controlled with full power in a normal go-round. It was the extreme trim condition which exceeded the elevator authority. As 'certified' for use, the 737 is perfectly safe and easy to fly. Boeing should not be expected to build a system to cater for what appears at this stage to be gross incompetence.

FE - I don't think so. Full automatic g/a remains available from a 2 channel stall, I believe, although it would be ****** exciting and as I said before, I would not encourage selecting TOGA to engage that!

Thanks BOAC.
On the Embraer 170 it does. That's why I asked.

Can't find anything saying it does, so it probably doesn't.

Errare Humanum Est
 

The advent of daycare, child seats and airbags have combined in a significant number of hyperthermia fatalities where children have been left inside cars parked at work. The article includes discussion of the factors that result in an otherwise conscientious parent forgetting that their child is still in the back.

washingtonpost.com

The article makes for uncomfortable reading, but does a service in reminding us that an otherwise conscientious parent or pilot can make a fatal mistake.

100% Please,
This is just about the worst bs Ive seen on this entire thread.It really annnoys me.The 737 is a fine workhorse with extremely good dispatch rates.The only reason that its not statistically the safest commercial jet in history is that pilots keep screwing the pooch.You really do have to know what you're doing when you fly it.
Boeing works on the KISS(keep it simple) principle.You,the pilot,must actually fly the thing,theyll help you out when and where they can but they wont hold your hand and if you screw up..dont call.

Dome light should never flash(more bs).I see no reason for including RA's in the comparator warning system(Baro alt,heading and AS are covered already..theyre your primary instruments).As for alpha floor,they have it but again its designed to be flown and controlled by the pilot.
Crude?You mean simple.
Nasty?You mean small flight-deck with no lunch table
Incapable during non-normal?You mean no ECAM checklist where you as a pilot dont actually have to think,reason and decide all on your own.

Back to topic.
Rainboe's comments,whilst correct,should not refer to crew directly or assign blame.The Dutch will work out what went wrong and the probable cause.Rainboe should not underestimate the little traps of automation that can confuse good pilots.The well-known ALT ACQ trap;on a GA if ALT ACQ is captured prior flap retraction the speed will revert to current speed in which case you could end up with flaps UP and not enough speed.Theres another stall scenario.Or if you approach FAF platform in VS and set missed approach alt in the window whilst still in ALT ACQ,the plane will maintain its VS rate and fly right into the ground.CFIT trap.
Personally,the failure to see RETARD instead of the normal MCP SPD on the AT FMA is minor although it would have spoken in volumes;a lot of people would do that.I think Airbus guys wouldnt because they rely more on what they see due feedback in limited channels.Its the failure to monitor A/S that is key.

Stall recovery is second.
i)How immediate was the response?Time in seconds from shaker-onset to recovery attempt.
ii)AT not disengaged?Why not?Startle factor..seat position.

EFSM(elevator feel shift module) hasnt been mentioned.Works above 100'RA with AP off and increases pressure to elevator feel computer to prevent pilots aggravating a stall situation.How much use?Would it have triggered considering the RA false reading?

having read the thread.......
 

I don't know what caused this crash - no one does yet, maybe the investigators are close but this is a rumour network, so I think its reasonable to state some possibilities.

1. It wasn't caused by one thing - be it RA failure, pilot error, training flight. We know from life in general, and aviation in particular that a chain of events has developed - nothing broke that developing chain- not crew action, not computer, had that been possible this event would not have occurred.

2. To those who say training should not be allowed on commercial flights, ok, but think it through, the consequences of doing this include many more planes in the air, many of them empty, increased fares for pax, increased global warming for everyone - not acceptable.

3. Everything we do in life is a risk, our job as professionals is to minimize that risk. Note- I'm not suggesting we can eliminate the risk because we can't - the closest we can get to elimination of risk is to stay in bed all day, and even that poses the risk of hypostatic pneumonia.
To minimize risk we need to train (=practice) and make mistakes, remember we learn more from our mistakes than anything. The trick is to make these mistakes in a safe environment- be it simulator or real world.

4. There is a constant tension between cost and thoroughness - and we need to decide where on this continuum we place the acceptable norm. The "bean counters" will try to make us accept more risk in return for cost savings- that is their job, and they are good at it. However, they are not the ones sitting at the pointy end in the middle of a freezing dark night in the middle of nowhere - the pilot carries that burden. The "bean counters" genuinely do not understand - they understand statistics, graphs, spreadsheets, and use these tools to constantly shave off cost in the name of efficiency.
Aviation is very safe, look at the bean counters graphs that prove it. However, that 0.01% on their graphs are real victims in real accidents.
Eventually nothing more can be shaved in the name of efficiency.

5. The human/computer interface isn't quite right yet, at least not in all cases. Pilots initially learn to fly a simple plane with little in the way between the flight controls and the pilot-aviate,navigate,communicate. As we transition through complex singles to twins to jets we are taken further and further away from these basic skills, as we accept more and more help from automation, which most of the time gets it right. The real skill is in understanding how this technology can help us, and maybe more importantly what to do when it fails. If we can't do this we are in trouble, we may never know it because the holes never line up in the cheese, but when they do, the consequences are tragic.

Solutions - generally I think we need to look at increasing our understanding of systems and their failures-diagnosing them, and indeed treating them. If we don't diagnose the problem, then we can't treat it, and the problem will get bigger until it becomes fatal.
In this specific case, had the RA failure been diagnosed correctly, then someone on the flight deck should have known that the automation (AP/AT) was dependent on that RA and the likely consequence was a throttle retard for flare - diagnosis leads to treatment - do something about it - fly the plane. This link in the chain would have been broken, and the accident would have had a much greater chance of being avoided.

The workload at EHAM is a minor link in the chain, maybe lower workload and more time would have helped, but i personally doubt it.

Sadly, the investigation is likely to look for simple answers to complex problems, and the temptation is to blame the pilots-nice and neat, simple recommendations and no one has too much work to do to put the bigger links in the chain right.

I'll get my coat.

aS BOAC told me, we're turning round in circles and I think this is the closest to the heart of the matter that we're going to get , for the moment, till new relevant information is available.

theamrad
 

So we can perhaps add pax comfort to ease and convenience as reasons for using A/T on the type of approach flown. But I'm having trouble reconciling fairly castigating this crew for their apparent poor monitoring of speed and thrust setting, with a justification for using A/T based on the perceived difficulty of qualified crews to manually coordinate speed/thrust with an autopilot flown approach.

MU - it is confusing, I grant you.

Firstly, it is easy to fly manual throttles on an autopilot coupled approach - it is just discouraged by operators. I do not agree with theamrad's statement. It requires more monitoring also but does not really adversely affect pax 'comfort'. The autothrottle takes away a lot of the effort but CANNOT be left alone without monitoring.

BOACOther posters have said that although certainly a hard work, TOGA power can be used. Are some of you current pilots saying you would be able to use TOGA in a low level stall and still maintain control the aircraft, whereas others say that you could not use max power? Sounds like I might have to be careful with whom I book my next holiday.

OK. I am probably out of touch now having retired ten years ago. But it does strike me as bizarre that an aircraft can be certified if max (symmetrical) power cannot be used at ALL STAGES OF FLIGHT.

Standing by for the flak.

Rainboe wrote:

You're right of course. But one thing strikes me as "weird". If A/T is on power idle, the pilot pushes the throttle levers to full power, and A/T then goes to power idle, then we would have a scenario where the pilot and the A/T disagree about the power setting. Pretty simple, isn't it?

Now, the question is: "Who should have authority in this case?". Forget this accident for a moment. In general, who should have authority, the pilot or the automation? (And yes, I know the pilot could disengage any automation if he like)

If the answer is "The pilot is always right and should always have authority over any automation". Well, then any automation should auto-disengage on pilot intervention. Doesn't that make sense?

It reminds me of a scenario where I was trying to reboot a Windows Server. The server wouldn't let me, for some strange reason. I had the authority to pull the power cord, and so I did. IMHO automation sould never question an operators (pilot) authority. The captain is in charge, not the electronics.

The intended result can be achieved by overriding the thrust levers by pushing them forward and keeping them there or disengaging the A/T and moving the TL forward.

LMAO!
Excellent.

Jack - no, max power it is. The confusion arises over the term 'TOGA'. On the 737 there are buttons which select TOGA power. It is that this TOGA press does other things involving flight directors and the like and the manufacturer's recommendation is a manual setting of max power ('straight arm'), PNF adjusts as necessary, while PF wrestles with the machine, flying basic pitch attitudes. The flight directors will not give useful information for a stall recovery. Once that is complete, the F/D can be reprogrammed to your heart's content. On a 'standard' g/a, pressing the buttons is fine as the F/Ds will give the right commands. Max power applied at a lowlevel stall will, as you should see above, while recovering you from the stall, make the a/c a handful and will also produce a huge nose-up pitch.

Bobcat - it is fine as it is. I think having it 'give up' the moment you touch the levers would be a mistake. It would only have taken a momentary press of a button to get manual control. We also get quite a lot of 'sticky' throttle movement due to friction where the throttles do not respond finely to the A/T demands and such a function might interpret this as pilot 'interference'.

Silly SLF question : What are the main things to watch out for if you go for max thrust in a stall. Shouldn't you retract gears and flaps ASAP or should you leave flaps and/or gear as they are and just watch out the nose doesnt rise too much and just let the power get you out? Just SLF here. I should think the main thing is to build speed and altitude ASAP?

p.s. edit: think BOAC may have just answered my Q about max thrust anyway.

jackharr wrote:
As a non professional pilot, even I know that max power cannot be used at all stages of flight. The fist thing I thought of was an emergency descent after pressurization failure. Come to think of it, any descent with full power would be bad. And not even when descending. With the immense amount of thrust available in these birds it's easy to overspeed. I would dare to say 100% power is very rarely used on a normal flight. Perhaps except at short runway take-off.

Not sure I did, 94116! However, no configuration changes are made until you are safely climbing away under control, for at least 2 reasons:
1) Gear stays down in case you touch the ground in the recovery when it will absorb some of the impact (yes, I know about muddy AMS, but in general). There is more than enough power available.
2) Raising flap and gear:
a) is distracting - 100% concentration required from both crew on flying out of the stall
b) can cause further pitch trim changes

This works fine in a car, but isn't really applicable in an aircraft. Having AP and AT that automatically disconnect on manual input might sound like a good idea but there is another factor maybe you don't consider. Suppose that someone accidentally nudges the yoke or a throttle and doesn't notice it? I can recall at least one CFIT incident where this happened and the aircraft flew gracefully into the ground while the crew were unaware that it was no longer on AP.

If you think about it the way it actually works is very sensible: if you make a manual control input it lets you do it, assuming there is some urgent need, but if you don't follow up by explicitly disengaging the automatics it assumes that you don't intend to continue manual control and gets back to automatic control.

Over at Boeing and Airbus there are thousands of experts who work full time on developing these systems. Some of the things they do might appear daft to outsiders, but often there is a reason for things working the way they do.

MU3001A and BOAC, just for clarification,
I didn't mean to imply that I believe passenger comfort to be part of the criteria concerning A/T off - A/P on approach. Nor would I think of it in terms of convenience - except where we would take that to mean that A/T use allows us more 'freedom' to reprioritise monitoring - and also ease the workload.

I wouldn't suggest A/T use for that reason at all - but who could deny A/P driven 'pitch hunting' because the FCC's have no A/T input if not coupled - esp with turbulence or gusts and trying to maintain a changing target thrust.
Personally - my point would be to stick to all on (coupled) or all off - in accordance with AFM, etc. Not just because I understand/believe Mr. B's design philosophy/architecture - but it also makes the most sense to me.

BOAC --
Also discouraged by Boeing. But actually I'm not sure what there is for you to disagree with me on here - I agree wholeheatedly with what you're saying here - if we accept that the passenger comfort part isn't really a consideration here.

Better a Fail Warn in View than a False Indication
 

I'll be posting a fairly thorough explanation of the Radio Altimeter within a few days. Meanwhile, consider this:

If a sensor, such as the radio altimeter, is giving you erroneous information, you have the option to disengage its circuit breaker. That way, your brain won't be trying to integrate erroneous, nonsensical data, and further bogus alerts will be silenced. . The automatics such as GPWS, autopilot and autothrottle won't be relying on false data, either. They will look to the backup sensor, if equipped.

If radio altitude errors persist, such as reported at THY, then the C check and corrosion control programs should be reviewed.

GB

AoA Indicator?
 

I asked this question about the AirBus on the Perpignan thread and never got an answer. Now I'll ask it here. Is there no AoA indicator in the 737 cockpit?

It would seem to me that stall recovery would be best accomplished by flying a specific AoA rather than pitch. AoA would compensate for aircraft weight, power setting, and probably some other parameters.

BOACAh, I'm understanding better. So TOGA is not simply "Take Off and Go Around" Power but implies all the others things as well such as Flight Director giving appropriate pitch attitude after take off? I honestly can't remember now after all these years just how we used the term TOGA in the 146

Application of TOGA with all the "add-ons" that implies, might be instinctive close to the ground but in some circumstances, such as stick shaker, is clearly not appropriate. "Firewalling" the throttles (no doubt, even more power than with TOGA) would be the correct response to a low level stall but it might not be what pilots would immediately think of.

I go back to when I instructed on the Varsity in the 1960s/early70s. We would practice stalls in the approach configuration. If I remember correctly, the drill was: Full Power - Flaps to intermediate position - when climb established, Gear up. Would seem to be a good drill for any aircraft.

It does seem that all this modern automation leads to the possibility of mindlessly obeying the "computers" and not thinking outside the box. I am not alone in making this point.

RadAlt Problems Noted?
 

I don't think anyone ever noticed the RadAlt problems on this or any of the previous eight flights. If they did, I don't think they reported it.

bobcat4Of course you wouldn't do that. But what I meant is that it should be possible to use full power at any stage of flight without losing control.

To deltayankee regarding car on cruise : Reminds me that when you have cruise on in your car set to say 75mph and you punch the gas pedal to pass and go past 75 and then you may want to drop speed below 75 as you tuck in behind that truck but the cruise keeps you at 75 and this could cause momentary confusion while you are watching out for traffic. Could it be that having half auto and half manual control of a moving vehicle leads to confusion if your attention is on something else? I guess more training would help in this regard. But it must be more complex when some systems are set to do certain things when you do something manually and you forget that it will do that.

IN Congonhas (and a few other similar incidents) the crew forgot to bring both TL to idle on touchdown (their minds were on other seemingly more pressing watch out factors ) and thus the machine ,by design didn't know they intended to come to a complete stop and didn't allow all its systems towards that end.

To BOAC thanks. What is your take on the Ci676 stall and non-recovery on Feb 16,1998 at CKS on an A300-600? Seems to me they didn't watch their speed on approach and got into a stall they shouldn't have and then fiddled with the configuration and went to max thrust but didn't watch the nose. One wing dropped and then confusion reigned all the way to the ground. A possibly faulty altimeter apparently got them 1000 feet too high on the glide slope and the subsequent go around was mis-handled? I take it that they should've left the configuration for the moment, BUILT SPEED and watch the nose to get out?

What lessons can be applied to this latest stall/crash?

AG RVS - The Crash of Flight CI676

Please scroll down in the link to the timeline. Thanks again.

@BOAC #1916

Is it only distruction of the crew or insane loss of lift due to retraction of flaps? Lift keeps you aloft, thrust gives speed to produce the lift, no? If you are at stall speed in landing config and you retract flaps you fall out of the sky don't you?

BOAC: "it is easy to fly manual throttles on an autopilot coupled approach."

I figured as much, thanks for confirming from experience.

The equipment I fly does not incorporate A/T so perhaps I'm biased against from the git go, simply due to unfamiliarity. However it does seem to me that A/T adds a layer of complexity not present with the manual application of power. If this added complexity - at a level once removed from direct control - leads to increased safety under all operations where A/T use is permitted and even required, then all to the good. But are there not routine operations where the utility of A/T violates the KISS principle allowing the potential for introducing yet more holes in the cheese only to be exposed when least helpful to a successful conclusion of the flight?

I wonder also if in this instance the presence of a training captain and the imposition of a checking regime perhaps intimidated the handling pilot into continuing with the automation when under different circumstances he might have reverted to some level of manual control? Perhaps the CVR will enlighten us?

Deltayankee, if you nudge the yoke enough it will indeed disconnect the A/P. Not the same story with A/T though disconecting these by moving them can theoretically be achieved, under certain circumstances already posted, it has little or no practical use.

MU3001A, my perception is that introducing A/T it's not like adding more holes, as I see it, you remove some holes and introduce new ones in a different spot. The trick consists in introducing less holes, or in a better place than what you remove.

automation masks poor flying skills
 

I think using automation is a way to lessen the skill levels required to perform in the cockpit.

I think that many manufacturers of airliners have tried to simpligy things so that piloting becomes more of a minor skill rather than a dedicated calling. Indeed, we see reductions of flying time at every level of flight.

Those pilots who once were highly skilled are becoming automated out of being good pilots.

SADly, at the time when you need the skills, they are now gone...whether it is stall avoidance or recovery.

Stall recovery is not that hard. Firewall power and minimize altitude loss while the plane accelerates. Certainly, the old method of stall recovery, pushing forward on the yoke works too...if there is enough altitude.

Much has been made of the nose up tendency with the application of power on the 737...anyone who has ever flown the plane knows about this and should be ready.

I blame the industry that wants to make skilled pilots something of a bygone era. Sad.

bobcat4:

Fully agree with bobcat4, normal "system" behavior would be to diengage the automatic setting when there is manual override applied. This seems not the case with the NG.

Could the plane have crashed because the captain just needed three arms? TL, stick and trim back the AP settings?

Perhaps he just did not trim back assuming that AT would disengage when TL are moved by hand? Still very hard case with the amount of hours he had. And too simple considering all the training...