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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 25th Apr 2019, 17:58
  #4321 (permalink)  
 
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Originally Posted by nyt View Post
So, do you still consider MCAS an STS subsystem ?
That was actually Boeing's position, not mine. That being said, there are regime's in which the traditional STS is inhibited, and regimes in which the MCAS is inhibited. These regime's are mutually exclusive.
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Old 25th Apr 2019, 18:06
  #4322 (permalink)  
 
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Originally Posted by edmundronald View Post
So above-average pilots would have saved the plane and below average pilots lose it.
Someone may have said this, but that is certainly not my position.

Let me restate it. There are certain expectations of a professional pilot who is entrusted with the lives of their passengers and crew. One of those expectations is that, in the presence of an unexpected aircraft state, they should be able to demonstrate the basic airmanship skills of hand-flying their aircraft by establishing the appropriate attitude and power settings, monitoring aircraft performance (speed, altitude, rate of climb, etc), and keeping the aircraft in proper trim.

This is an expectation for ALL professional pilots. Not above average. Not average. ALL.
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Old 25th Apr 2019, 18:06
  #4323 (permalink)  
 
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I certainly agree with your comments about the hand flying skills.
On an 8 hour atlantic sector how much time does a pilot actually fly the aircraft ?, 5 mins, bit more bit less ?.
How out of practice do you get after 5 or 10 years of just systems management ?.
I know some commercial pilots fly light aircraft for fun, but how many dont ?.
I think all commercial pilots should have to fly a manual light aircraft and fly some aerobatics at least 5 hours a year.
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Old 25th Apr 2019, 18:10
  #4324 (permalink)  
 
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Clueless posts drowning out the valuable ones

737 driver is obviously a professional pilot flying the 737. As a 737 NG Captain myself I can assure you he knows what he is talking about. He is an expert on the subject and the majority of the posters arguing with him are not. It is amazing and at the same time quite frustrating to observe the conviction with which people are stating their opinions on here even though they are actually clueless.
Instead of posting your ignorant armchair pilot comments, why don't you take some time to read up on the procedures to fly the 737. Read the official Boeing documents. Talk to 737 pilots and ask them how they are trained. Of course this will take a lot longer and require much greater effort than posting your oblivious comments but then you might be a little bit closer to actually being able to judge how these pilots performed.
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Old 25th Apr 2019, 18:22
  #4325 (permalink)  
 
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Originally Posted by GordonR_Cape View Post
- MCAS was designed to activate at a much lower AOA, independent of the stick shaker.
- MCAS was designed to activate under many areas of the flight envelope, independent of the stick forces and airspeed.
2 things -

1) Do you have a reference for what AOA MCAS activates at when compared to the stickshaker AOA, preferably from a primary source, i.e. the manufacturer, a regulatory body, or similar? I've looked for that but have been unable to find it... it's getting difficult to find original data among all the poorly written media interpretations.

2) I do not believe that is true. Airspeed is used both as in input to determine the MCAS activation AOA, and it is used to determine the magnitude of the stab trim input. The first time that we learned anything about MCAS was in the November 8/9/10 timeframe in a letter from Mike Michaelis, APA safety committee chairman. It was an unpublished letter to APA members but was extensively reported in the media, and claimed to include a description of MCAS that was provided by Boeing. Here's a contemporary PPRuNe link - Indonesian aircraft missing off Jakarta

The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers. The function is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.



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Old 25th Apr 2019, 18:23
  #4326 (permalink)  
 
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Hmmmm, is he the same as the 4 professional pilots who were flying the two planes that crashed ?.
Maybe all of those 4 were below average, and he is above average ?.

Being professional in any job doesnt make you automatically good at it at all. it just means you get paid for it.
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Old 25th Apr 2019, 18:30
  #4327 (permalink)  
 
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Originally Posted by 737 Driver View Post
That was actually Boeing's position, not mine.
That's also the FAA's position, at least based on the most recent FSB report draft. https://www.faa.gov/aircraft/draft_d...ev17_draft.pdf

B-737-MAX Maneuvering Characteristics Augmentation System (MCAS). The Speed Trim System (STS) provides speed and pitch augmentation. Speed stability augmentation is provided by the Speed Trim function of STS. Pitch stability augmentation is provided by the MCAS function of STS. MCAS ground training mustaddress system description, functionality, associated failure conditions, and flight crew alerting. These items must be included in initial, upgrade, transition, differences, and recurrent training.





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Old 25th Apr 2019, 18:43
  #4328 (permalink)  
 
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Originally Posted by edmundronald View Post
So above-average pilots would have saved the plane and below average pilots lose it. Let's see, there are 50% of below average pilots in the world, you better be careful when an SLF to get in the right plane - although of course only above average pilots participate in PPRuNe.

Gimme a break - the issue is why were the pilots subjected to this horrible situation, where being average but not good meant bye bye for the SLF?

Edmund
Average professional pilots even below average professional pilots should note and correct out of trim flight. This is C-172 stuff and is not complicated. The first Lion Air flight showed that the Max with MCAS erroneously operating is flyable by repeated trimming, the second flight showed that had the captain continued trimming back to in trim the flight may not have crashed; it was only when the trimming was reduced to the occasional blip that control was lost. If trimming had continued and a return to airport was chosen as soon as the flaps were lowered MCAS would have stopped and the aircraft could have recovered.

Boeing had an expectation that qualified 737 pilots would continually keep the aircraft in trim and that would stop MCAS, They also had the expectation that repeated uncommanded nose down stab trim by the aircraft systems would result in the stab trim being switched off by a qualified 737 pilot. Boeing was wrong. 737 pilots qualified and allocated their seats by their airline did not do as Boeing expected. It seems that automation surprise plus all the alerts aural and haptic (the stick shaker) amplify the automation surprise to a level where some pilots can no longer 'fly the plane'. It may be that the simulation training may not provide the visceral reality of an emergency in the real aircraft resulting in cognitive tunneling or even an attempt to carry on as if the system failure hadn't happened. I and no doubt others here, have witnessed examples where competency shown in the simulator falls apart in the 'real world',

So while Boeing is building aircraft that would be easily flyable by 737 pilots from the 1970's who usually flew manually and often preferred to switch off the automation; the training systems and the airline training constraints are producing pilots who avoid and are instructed to avoid, manual flying and who are better at system management. This has become apparent in this thread where there is a rough distinction between the 'switch it off' - pitch and power - fly the aircraft group (smaller); and, the systems managers who need to know all the aspects of the system with an FMEA and NNCs geared to each of those failure modes. The first group are aghast the aircraft were not recovered, the second are aghast that a new part of the system was not flagged up by Boeing and was not briefed with precise NNCs.

Aviation seems to have met the cross over point where avionics manufacturers and airframers can no longer assume that any bag of bolts on failure will be picked up by someone 'aviating', 'navigating' and 'communicating' - setting pitch, power, trimming and flying the aircraft; they now have to remove all potential single-points-of-failure, fail soft, gracefully degrade, and, if possible automation should carry on and cope with all potential failure modes. However, that is a slippery slope as it is a self fulfilling prophecy the more capable the automation the less capable the pilots. The only ones happy about that are the beancounters who will further reduce simulation time accelerating the problem.

Last edited by Ian W; 25th Apr 2019 at 18:45. Reason: grammar
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Old 25th Apr 2019, 18:51
  #4329 (permalink)  
 
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Originally Posted by 737mgm View Post
737 driver is obviously a professional pilot flying the 737. As a 737 NG Captain myself I can assure you he knows what he is talking about. He is an expert on the subject and the majority of the posters arguing with him are not. It is amazing and at the same time quite frustrating to observe the conviction with which people are stating their opinions on here even though they are actually clueless.
Instead of posting your ignorant armchair pilot comments, why don't you take some time to read up on the procedures to fly the 737. Read the official Boeing documents. Talk to 737 pilots and ask them how they are trained. Of course this will take a lot longer and require much greater effort than posting your oblivious comments but then you might be a little bit closer to actually being able to judge how these pilots performed.
I'm not a pilot, but also not clueless (having both an engineering and programming background), and having read all 4000 plus posts in this thread. My questions have not been about how to fly a B737, but how the MAX and MCAS actually work, with stuck high AOA data. No pilot on this forum has actually experienced this, either in person or in the simulator. I (and others) do not accept as verbatim truth, the system descriptions provided by such pilots, however experienced. The same applies even more to Boeing, who were evasive about the existence of MCAS, provided limited documentation, and have much to gain by shifting blame, and good (legal) reasons for not disclosing more details.

Only an independent engineering verification (not paper documents and diagrams) of the details of systems involved in the crashes, and of the proposed revisions to MCAS, will provide all the answers. My viewpoint has nothing to do with blame, just looking for the truth, which may take some time (years?). In the meantime any assertion that the pilots should have done X, can be countered by an assertion that perhaps the software or hardware did not allow that to happen. The same is true of any crash investigation, where both complex systems and human factors were involved.
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Old 25th Apr 2019, 19:05
  #4330 (permalink)  
 
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Originally Posted by GordonR_Cape View Post
I'm not a pilot, but also not clueless (having both an engineering and programming background), and having read all 4000 plus posts in this thread. My questions have not been about how to fly a B737, but how the MAX and MCAS actually work, with stuck high AOA data. No pilot on this forum has actually experienced this, either in person or in the simulator. I (and others) do not accept as verbatim truth, the system descriptions provided by such pilots, however experienced. The same applies even more to Boeing, who were evasive about the existence of MCAS, provided limited documentation, and have much to gain by shifting blame, and good (legal) reasons for not disclosing more details.

Only an independent engineering verification (not paper documents and diagrams) of the details of systems involved in the crashes, and of the proposed revisions to MCAS, will provide all the answers. My viewpoint has nothing to do with blame, just looking for the truth, which may take some time (years?). In the meantime any assertion that the pilots should have done X, can be countered by an assertion that perhaps the software or hardware did not allow that to happen. The same is true of any crash investigation, where both complex systems and human factors were involved.
There are two issues at hand here: One issue is everything surrounding MCAS which you are interested in. Another issue is, if these accidents were preventable by carrying out the required Boeing procedures or by applying basic flying skills respectively, despite MCAS activating.
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Old 25th Apr 2019, 19:09
  #4331 (permalink)  
 
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Originally Posted by Loose rivets View Post
Posted in error on the parallel thread.

737Driver
post number #4304
Quote:
One of the bees in my bonnet has been the removal of that column switch on the MAX. Not just the bypassing of its logic under certain conditions - but the total physical removal.

Despite being in my 80th year, (and posting on the wrong thread) statements like that still stick firm, like the unwinding of MCAS. The switch removal (from under the floor at base of column) never really got a clear answer. Well it did: a dedicated post saying 'I don't know'.

I try to filter my information input, and of course a lot is from the Times publication and our engineering friend in Seattle. The switch is either there, or not there, but it seems if it is, its functionality can be obviated as per 737 Driver's earlier post.

Back to his assertion that it was flyable. I get a sickening feeling that something else apart from psychological overload might be wrong. There are so many able minds chasing the suspected faulty input to that 47' of flying surface, along with the associated loading difficulties, that you'd think remedial action was just a matter of time. But the thing I fear most is months of rewriting of code, some agreement on what is now certification and the craft back in the sky carrying a ghost in the machine.

There is too much pressure to get airborne.

'We' seem to have everything we need to throw light on those terrible moments, but the very fact that so many skilled people, not least of all on this forum, can disagree on the extent of the pilot culpability worries me deeply. There is a huge dichotomy in the judgement of these flying professionals.
It is the last paragraph of the above post that also concerns me. I am dismayed to read on this forum that there are those who suspect culpability on the part of the pilots. Here is an extract from Dominic Gates article in the Seattle Times

"Flawed analysis, failed oversight: How Boeing, FAA certified the suspect 737 MAX flight control system"As Boeing hustled in 2015 to catch up to Airbus and certify its new 737 MAX, Federal Aviation Administration (FAA) managers pushed the agency’s safety engineers to delegate safety assessments to Boeing itself, and to speedily approve the resulting analysis."

The full article may be accessed at : https://www.seattletimes.com/busines...ion-air-crash/

"But the original safety analysis that Boeing delivered to the FAA for a new flight control system on the MAX — a report used to certify the plane as safe to fly — had several crucial flaws."

How could it be that when so much has been published about this accident, some can still consider culpability may still be suspected on the part of the pilots. Is this not yet another case of a race between competitors, just as it was back in the late 60`s, early 70`s for the first wide body jets and the Turkish DC10 crash.
Always easy to blame the pilots, perhaps this is why in today`s age of high tech, computers, robotics, automation, that pilots are still "carried" on board the modern airliner.


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Old 25th Apr 2019, 19:16
  #4332 (permalink)  
 
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Originally Posted by edmundronald View Post
So above-average pilots would have saved the plane and below average pilots lose it. Let's see, there are 50% of below average pilots in the world, you better be careful when an SLF to get in the right plane - although of course only above average pilots participate in PPRuNe.

Gimme a break - the issue is why were the pilots subjected to this horrible situation, where being average but not good meant bye bye for the SLF?

Edmund
Perhaps "below average" pilots shouldn't be hauling live cargo? Or - perhaps a "below average" pilot can still competently fly a malfunctioning aircraft. I'm not willing to accept that the spectrum of commercial airline pilots include, as "below average," pilots who cannot do what many recognize here would have saved the day (and what the penultimate Lion Air crew was able to do). But - if that's where the industry is headed - perhaps the aircraft do need to be smarter and in more control . . . .
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Old 25th Apr 2019, 19:17
  #4333 (permalink)  
 
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As I said previously, it's about MONEY, and shortcuts, and covering up as much shit as they can to try to minimize the massive law suits that are now in progress.

Self certification...............WTF..........how is that ever safe.
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Old 25th Apr 2019, 20:01
  #4334 (permalink)  
 
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The "children of the magenta line" is a real issue in my opinion, but I do not think that it has anything to do with either crash. There is no evidence that the pilots were deficient in hand flying -- that may be a surprising statement to some who have been following this discussion, but "hand flying" doesn't mean "physically crank on levers and wheels to control the aircraft's control surface." That is what the pilots were being asked to do because there was no way to turn off HAL -- all they could do was bypass him by crippling the same controls that they were using and revert to the emergency backup. However, it was not even that simple, now we are being told that the mistake of the Lion Air pilots is that they turned off the power trim system too early and instead should have used the power switches to revert the trim and then turned it off while at the same time blipping it to reset MCAS-- which is what it appears that they were tying to do just before the plane pitched nose down into terrain as HAL came roaring back.

The emergency manual backup wheels that they were expected to use is so disregarded that most modern planes do not have it and was allegedly made smaller in the NEO in order to make space for the display screens. I see an analogy to a modern ship's wheel which is hardly ever touched because everybody uses the hydraulic systems that are part of the ship's autopilot. That doesn't mean that captains are always steering the boat by entering courses into the autopilot or worse, are children of the magenta line, it just means that there is no point to trying to turn a large ship by cranking like the devil on a relic from the days of square rigged sailboats and 100-person crews. If a captain were slow to realize that his NFU (non-follow up control, the way that you use power steering) control was sometimes slipping in a few extra degrees of turn than what he commanded we would not put him in the same class as a pleasure boater whose only experience with navigation is to touch points on the Garmin screen and then hit "engage autopilot." He or she may have been deficient in diagnosing the problem, or deficient in noticing that the ship was headed somewhere other than commanded, but that is an entirely different issue and one that probably relates more to experience.
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Old 25th Apr 2019, 20:16
  #4335 (permalink)  
 
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Originally Posted by WillFlyForCheese View Post
Perhaps "below average" pilots shouldn't be hauling live cargo? Or - perhaps a "below average" pilot can still competently fly a malfunctioning aircraft. I'm not willing to accept that the spectrum of commercial airline pilots include, as "below average," pilots who cannot do what many recognize here would have saved the day (and what the penultimate Lion Air crew was able to do). But - if that's where the industry is headed - perhaps the aircraft do need to be smarter and in more control . . . .
Everyone makes mistakes at some point or another, especially under stress. I personally try to keep myself at least 2 or preferably more mistakes (mine or others) away from a bad outcome, driving, woodworking or whatever.

The ET crew made one or more mistakes, not all of them significant, Sully succeeded despite neglecting to set transponder code.

One probably significant one was loss of awareness/control of speed, which contributed to inability to manually trim.

It is possible they decided stick shaker was spurious and since the speeds were not all that divergent (until later) they may have discounted uas warnings, hence attempt (and success for a while) to use autopilot which probably reinforced 'spurious' impression.
Had they been perfect they would have kept flaps down etc, although if they "perfectly" reacted to stall warning it might not have gone as well.

They did follow the runaway trim procedure but were apparently unable to manually trim then lost it when re-enabling electric trim.
Lack of manual trim and inability to disable only automatic trim (as on NG) was someone else's mistake, not theirs.

So how many mistakes are allowed? One hopes the number is greater than 1.
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Old 25th Apr 2019, 20:38
  #4336 (permalink)  
 
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On average

Heard tell that ex President Bush was very upset when told that about half of american students were below average in math.

There is a spectrum of skills and abilities in every field. The hard part can be drawing a distinction between 'below average' and incompetent.

One other datapoint is that something like 70 percent of drivers consider themselves above average.
While I don't know the stats for pilots, any professional pilots reading this thread consider themselves below average?

Of course mathematicians get upset with generic use of the term average (mean of them) but that is a different thread somewhere in a forum far far away.

Assuming normal distribution 75% of all flights have at least one below average pilot in the cockpit.

Last edited by MurphyWasRight; 25th Apr 2019 at 20:47. Reason: Added 75%
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Old 25th Apr 2019, 21:01
  #4337 (permalink)  
 
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Originally Posted by 737 Driver View Post
I had the exact same question when I first read the accident report. I spent a lot of time looking for evidence that the trim motor stalled or the trim switch wasn't working. However, none of the accident evidence or any historical data supports either of these conclusions.

One of the most telling pieces of evidence in this report, however, is that the Captain repeatedly tried to engage the automation (three times) in a situation that specifically precluded it. This is evidence of someone with a strong case of automation dependency. People with significant automation dependency also demonstrate a deterioration in basic hand-flying skills. Combine that with the startle effect and the distraction of the active stick shaker, it is entirely conceivable that the Captain suffered from cognitive overload and simply forgot to trim because it had never become a thoroughly engrained behavior.
Four times.
Take a look at 05:43:15, just after they made those two insufficient trim inputs. They got a warning there from a failed attempt to engage the autopilot.

Unfortunately the report has left out plenty of what was said and done in that last phase when they lost control.
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Old 25th Apr 2019, 21:32
  #4338 (permalink)  
 
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Originally Posted by MurphyWasRight View Post
Heard tell that ex President Bush was very upset when told that about half of american students were below average in math.

There is a spectrum of skills and abilities in every field. The hard part can be drawing a distinction between 'below average' and incompetent.

One other datapoint is that something like 70 percent of drivers consider themselves above average.
While I don't know the stats for pilots, any professional pilots reading this thread consider themselves below average?

Of course mathematicians get upset with generic use of the term average (mean of them) but that is a different thread somewhere in a forum far far away.

Assuming normal distribution 75% of all flights have at least one below average pilot in the cockpit.
"Average" is relative - correct? Take US military service . . . there is an "average" soldier, and then, perhaps, an "average" Navy SEAL, or US Army Delta Force. Or, if you will, military of any country and, then, Canada's Joint Task Force 2; Denmark's Jaeger Corps; or Britain's Special Air Service . . .

The average of an elite group will always be above the average of a larger group. Indeed, the larger group may include those that shouldn't be in the armed forces at all. The more elite groups will all be more than competent - and each elite group will statistically have an average, below average, and above average.

My point was, and is, that commercial airline pilots should be an above-average group to begin with. Leaving the "below average" pilot not far off from the above average pilot - any one of which is highly capable individually. For many reasons - that is not how the profession has evolved. Low wages? Poor treatment? Perhaps the airlines themselves are to blame as well for degrading the profession?

I digress.
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Old 25th Apr 2019, 21:42
  #4339 (permalink)  
 
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Originally Posted by Water pilot View Post
The "children of the magenta line" is a real issue in my opinion, but I do not think that it has anything to do with either crash. There is no evidence that the pilots were deficient in hand flying -- that may be a surprising statement to some who have been following this discussion, but "hand flying" doesn't mean "physically crank on levers and wheels to control the aircraft's control surface." That is what the pilots were being asked to do because there was no way to turn off HAL -- all they could do was bypass him by crippling the same controls that they were using and revert to the emergency backup. However, it was not even that simple, now we are being told that the mistake of the Lion Air pilots is that they turned off the power trim system too early and instead should have used the power switches to revert the trim and then turned it off while at the same time blipping it to reset MCAS-- which is what it appears that they were tying to do just before the plane pitched nose down into terrain as HAL came roaring back.
To me it appears that the last crash was a case of "magenta line".

1. Stall warning and stick shaker on rotation
Solution: tried to engage the autopilot at 400 ft

2. Apparantly false stick shaker due to erroneous inputs + unreliable airspeed
Solution: tried to engage the autopilot at 600 ft

3. Still stick shaker due to erroneous inputs from left side
Solution: finally succeeded to engage the left autopilot at 1000 ft

4. Aircraft is grossely out of trim and in an overspeed condition, making it hard to fly
Solution: tried to engage the autopilot


Last edited by Brosa; 25th Apr 2019 at 22:16.
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Old 25th Apr 2019, 22:08
  #4340 (permalink)  
 
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Originally Posted by MurphyWasRight View Post
Heard tell that ex President Bush was very upset when told that about half of american students were below average in math.
If you use "average" in the most commonly used sense meaning the arithmetic mean of a distribution then there is no reason why half of the population should necessarily be "below average".

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