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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 4th May 2019, 10:40
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uplinker #4860
I’m sure this will have been mentioned, so apologies but, is there an AoA disagree warning on the 737?

The $80,000 upgrade, and the warning that got lost in the mystery of not having that upgrade, will, I hope, become a courtroom issue.
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Old 4th May 2019, 11:25
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Originally Posted by Ancient Mariner
All this grandstanding makes me wonder if some of you have been in an emergency, a real emergency?
I've been fortunate/unfortunate enough to have been in a few, albeit maritime, not aviation related.
Everytime I was surprised to see "highly trained professionals", and I mean highly trained, we had realistic training once a week for these eventualities, totally break down and be unable to function. I not talking 30 seconds, 90 seconds, but unable, period.
Aviation is of course a totally different ballgame.
Per
I agree with your observation. I think we all aspire to function well under severe pressure or danger. The truth is even we cannot predict how we will operate under intense pressure let alone how somebody else will perform. Training does help, provided it is sufficient to make the actions required second nature but still does not recreate the pressure of facing death. I have been in a number of high stress situations and in hindsight performed reasonably well in two but failed miserably in another resulting in the death of a friend. My father was an resistance fighter during WWII and was accustomed to life and death situations for over 4 years of his life continuously. I always admired his ability to function under the most intense danger and pressure... but there is no training that can replace experience. Many people luckily do not have the benefit of observing themselves in the most extreme of circumstances.

I too have witnessed well trained peoples minds become empty and acknowledge all the training in the world cannot predict a poor reaction to the ultimate stress. From my own experience I can say that in the two circumstances that I performed well, I immediately had a clear crystalized understanding of what was required. In the event that I did not perform well, I was unsure of the best course of action at the time. What I find difficult to read in this thread are people that have assumed what happened and assumed that it was immediately clear to the pilots what was required. Flying pitch and power is a little more stressful when you are a few feet AGL. I will reserve judgment on the pilots until further information is available and even then do not believe that Boeing should have ever placed them in that situation.
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Old 4th May 2019, 11:34
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I accept that pilots are trained to react to certain situations in a manner that does not require them to make nuanced decisions. This seems eminently sensible. However, it seems to me that this requires pilots to be sure that they're reacting to the right problem. If you get UAS, along with a bunch of other anomalies you wouldn't normally expect, I think the human brain might hesitate to diagnose. The fact that performing the UAS memory items may have saved the day does not mean that this was clear to the ET crew in the moment.

In the Lion Air cases, crews had no idea MCAS existed, and struggled to make a diagnosis. The first crew 'happened' on a solution. The second crew had to factor in the plane's behaviour AS WELL AS the underlying knowledge that the a/c had misbehaved in a mysterious way the flight before.

The Ethopian crew were in a position to know that MCAS existed, although it seems their company had not provided them with much information. Like most MAX pilots, they would have had to think through for themselves - on their own time - how an MCAS anomaly might present. In the moment, with the cockpit screaming at them, they were - in real time - having to work out if this was an MCAS problem and whether this affected what they should do. Runaway MCAS is not quite the same as runaway stabiliser. Remember: at that time, MCAS had caused problems only once; Boeing had downplayed the seriousness of the issue and subtly blamed the third-world airline; despite the hull loss Boeing had not rushed to put a correction in place. The situation was foggy and confusing.

The crew was highly motivated to keep this plane safe. I'm sure we all agree on that? But Boeing's poor handling of the MCAS bad news may itself have contributed to the ET crash. The fact that, with their own lives on the line, these pilots were not able to work out what to do, suggests that crews needed proper training in how to incorporate MCAS issues into their diagnostic triggers. Pilots depend on training that reduces their startle response and allows them to diagnose quickly. Some pilots will need that more than others.
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Old 4th May 2019, 11:46
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Originally Posted by GordonR_Cape
Thanks for the interesting links, which together shed some light on the current discussion.

I would add another factor, the difference between procedural memory and semantic memory. Pilots will have been repeatedly trained to do certain procedural operations on NG simulators, which become part of ingrained muscle memory. With the introduction of the B737 MAX, there were insufficient simulators. Differences training was done on a computer, which became part of factual recall memory.

IMO the combination of procedural training on a B737 NG, plus semantic training of the MAX differences, may create a mental conflict in determining the right choice of actions. The addition of stress factors, would make the failure to respond correctly much higher.

Reference: Declarative Memory (Explicit Memory) and Procedural Memory (Implicit Memory) - Types of Memory - The Human Memory
Sounds perfectly rational to me.

Over the years I have been witness to some truly ignorant behavior by senior managers, and in turn the organizations they control. In basic terms, the one contributing factor to this baffling loss of corporate intellect, has been the AGENDA!

Did something similar happen at Boeing and the FAA?
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Old 4th May 2019, 11:49
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I said a bazillion posts ago that there's a chance some pre-knowledge of the Lion Air accident had a negative effect on the ET skipper's actions. Firstly a greater shock factor - due to realising a very specific and serious danger was confronting him. It may even explain, in those frantic moments, why he went for the AP. He may have picked up on the fact it would stop this mysterious MCAS, a problem he thought would not become an issue again in a million years. When at last the AP engaged, it would be only moments before his worst fears were realised. He was replaying the Lion Air accident, and things would be becoming surreal.

I've also mentioned finishing a flight with the stick-shaker going. I was in ink black chop and the noise seemed to suck at my mind, despite being one who loved a challenge to relieve the boredom.

Being in a 1-11 at Palma - V1 Rotate, and seconds later hovering over some buildings to the left. Zero on one ASI, and VMO on the other. We just kind of sopped over these grey hangar-like structures and then climbed away. I issued a met warning and company aircraft all went to Barcelona. And that was it. Nothing ever said about the incident. Even hopping over a bowser in Naples never got a single request for clarification. The bowser appeared out of the heat haze when we were very near V1. No worries, it'll be gone, and then the aaaaaaaagh moment. It was towing an even bigger bowser. Yes, another notch of flap on takeoff works. A bit of nervous laughter and we got on with our day. Different world back then.

The thing is, machines are machines, and they do much what we expect them to do - until one day they don't. But even then, minds world-wide can dig and dig at the probabilities as we're doing here. The mechanical side will make sense eventually, however unpalatable. However, the human side may never make sense. As I look back at my life, human behaviour has been the greatest mystery, and outside of war, my observation of unexplainable behaviour has not surprisingly been in the aviation industry. Bewildering, even unconscionable . . . I can't find a more suitable adjective, much of it to do with keeping the show on the road, or should I say, in the air.

If they do dig deep into Boeing and the FAA, it's probable I won't live long enough to see the last act of the performance. But the fact is, I could leave the theatre early because nothing would surprise me.
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Old 4th May 2019, 11:57
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Originally Posted by PaxBritannica
I accept that pilots are trained to react to certain situations in a manner that does not require them to make nuanced decisions. This seems eminently sensible. However, it seems to me that this requires pilots to be sure that they're reacting to the right problem. If you get UAS, along with a bunch of other anomalies you wouldn't normally expect, I think the human brain might hesitate to diagnose. The fact that performing the UAS memory items may have saved the day does not mean that this was clear to the ET crew in the moment.
Which is precisely why I and others have stated ad nauseum that when a pilot is presented with an undesired aircraft state, ambiguous warnings, or loss of situational awareness, they must be able to, at a minimum, Turn off the magic, Set the pitch, Set the power, Trim the aircraft, Monitor the performance, and Move to a safe altitude, i.e. FLY THE AIRCRAFT. This is the default response to any emergency or non-normal situation when a pilot is unclear as to what he/she should do next. And yes, it is a trainable response.

Performing these actions is no more difficult than executing the procedures for an engine fire/failure at V1, and we should not expect any less from a trained and competent commercial flight crew.
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Old 4th May 2019, 12:06
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Originally Posted by wheelsright
What I find difficult to read in this thread are people that have assumed what happened and assumed that it was immediately clear to the pilots what was required. .
What's immediately clear and overwhelmingly obvious is that when I'm pulling the control column to climb and the jet's not climbing but trimming nose down, is to stop the forward moving trim wheel either with my right hand or my right thigh/knee and simultaneously order the copilot to cut the stab trim switches. Just like that. Instinctively when the jet is not responding to my control inputs. Because for the moment I don't need to THINK nor to KNOW whether it's MCAS or just a runaway trim. It's elementary, instinctive hands-on flying reaction by an experienced pilot. The 29 year old purported 8000 hour captain seemed to be weaned on automation over-dependence and obviously lacked depth in manual flying skills. Turning on A/P with stick shaker, oblivious to approaching VMO at low altitude... Sad.

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Old 4th May 2019, 12:18
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737Driver, Matt48,
‘… evidence to suggest that the electric motor could stall under the loads …’
This may depend on the direction of applied load. MCAS ‘nose down’ could be easier than a resorting ‘nose up’ crew trim switch input. Similar problems for manual trim wheel, particularly if the elevator is deflected to demand aircraft nose up.
Also see the discussions about deliberate electric trim inhibition - https://www.satcom.guru/2019/04/what...-on-et302.html diagram of electric trim limit. Was MCAS wired through this restriction or not ?
The basic point was identified in the EASA certification query, which was answered as the alternative trim wheel input would be available
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Old 4th May 2019, 12:37
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Originally Posted by safetypee

737Driver, Matt48,
‘… evidence to suggest that the electric motor could stall under the loads …’
This may depend on the direction of applied load. MCAS ‘nose down’ could be easier than a resorting ‘nose up’ crew trim switch input. Similar problems for manual trim wheel, particularly if the elevator is deflected to demand aircraft nose up.
Also see the discussions about deliberate electric trim inhibition - https://www.satcom.guru/2019/04/what...-on-et302.html diagram of electric trim limit. Was MCAS wired through this restriction or not ?
The basic point was identified in the EASA certification query, which was answered as the alternative trim wheel input would be available
Again, no evidence from either of these accidents or from historical data that the electric stab trim motor could stall under load. The matter of the electric trim inhibition discussed in the link above is a completely separate issue. That inhibition prevents main electric trimming (pilot actuated) into a certain region of forward trim, but it does not prevent the use of electric trim to move out of that region.

All this being said, one of the causal factors of these accidents is that the pilots let the aircraft so far out of trim in the first place. It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb - if he had chosen to use it.
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Old 4th May 2019, 12:40
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Ad nauseam

737 Driver,
Ad nauseam is a Latin term for argument or other discussion that has continued to the point of nausea. … indicating that the topic has been discussed extensively and those involved have grown tired of it.

Repetition does not change the accuracy or value of a statement or argument.
People, aviation, the world is not absolute, thus by considering the in-between ‘grey’ area opens the possibility of identifying something to learn. It is up to us to take these possibilities, accept that there is always something new to learn.

Avoid ‘what is’, and consider ‘what might be’; accept that no single view is absolute, not applicable to all situations, particularly those which you did not attend.

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Old 4th May 2019, 12:52
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Originally Posted by alf5071h
737 Driver,
Ad nauseam is a Latin term for argument or other discussion that has continued to the point of nausea. … indicating that the topic has been discussed extensively and those involved have grown tired of it.

Repetition does not change the accuracy or value of a statement or argument.
Perhaps it's worth noting that repetition and practice are core drills behind many learned skills, including aviation. It seems that certain reminders are very much in order here.

"People need to be reminded more often than they need to be instructed." - Samuel Johnson
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Old 4th May 2019, 13:03
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Originally Posted by LEM
Fact is that even if your brain is short circuited by fear of death, that's exactly in those moments that pilots should be real pilots, I mean resource to INSTINCTS, BASIC INSTICTS.
A "pilot" who hears the tremendous noise of 500 knots (!) and doesn't even touch those tho things in the middle of the pedestal (also called trust levers) to pull them back.... well, should be doing another job (and I put it nicely)....
If you bothered to read the preliminary report you would have seen that they were not at 500 knots (!!!????!!!!). They only reached 500 knots immediately before impacting the ground, after diving for 20 seconds following the final MCAS activation.

Before that however:

"From 05:40:42 to 05:43:11 (about two and a half minutes), the stabilizer position gradually moved in the AND direction from 2.3 units to 2.1 units. During this time, aft force was applied to the control columns which remained aft of neutral position. The left indicated airspeed increased from approximately 305 kt to approximately 340 kt (VMO). The right indicated airspeed was approximately 20-25 kt higher than the left."

Which is consistent with the FDR IAS trace.
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Old 4th May 2019, 13:20
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Originally Posted by PaxBritannica
The first crew 'happened' on a solution. .
The crew did not happen on anything, It was a jump seat pilot from a different airline that told them what to do and saved the day.
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Old 4th May 2019, 13:38
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Originally Posted by James7
The crew did not happen on anything, It was a jump seat pilot from a different airline that told them what to do and saved the day.
I believe that's a pretty good definition of 'happening on a solution'. They tried other things unsuccessfully and then tried the suggestion of a third party, and it happened to work.
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Old 4th May 2019, 13:39
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Originally Posted by HarryMann
Forgive me but I don't believe this has been asked or answered before, so maybe I'm missing the basics but...

At stick shaker upon or immediately after take-off

Would raising the flaps be expected even when past V2 and apparently accelerating and climbing normally.
Surely an immediate return might be anticipated whilst I acknowledge a desire to cleanup and find a stable and mentally comfortable flight regime.

So surprised not to see this action directly criticised... I can see theres a conflict or choice between wanting adequate speed/thrust setting and sticking with a speed limiting flap setting (i assume).
Well, Yes & No.

The crew have 3 independent IAS indications, and the AOA information in passing by the lower limit speeds on the IAS tape. The AOA is incorrect, and that is triggering an erroneous correction to the Capt's IAS and triggers the disagree messages, the AOA already triggering the stall warning erroneously. The crew understand the aircraft is flying, and a cross check of power/attitude as well as comparison of the Capt/FO and the integrated standby would indicate that the Capts display is erroneous, and using the other sources, cleaning up would be possible. it is also possible that the crew were following established routine and raised the flaps. Once that was done the headaches multiplied rapidly. Either scenario is quite possible. Frequently, a crew will raise the gear after takeoff following a tyre failure or other issue that would contraindicate that procedure. We do tend to follow entrenched routine, even though such routines can be quite easily interrupted.


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Old 4th May 2019, 13:40
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Originally Posted by 737 Driver
Which is precisely why I and others have stated ad nauseum that when a pilot is presented with an undesired aircraft state, ambiguous warnings, or loss of situational awareness, they must be able to, at a minimum, Turn off the magic, Set the pitch, Set the power, Trim the aircraft, Monitor the performance, and Move to a safe altitude, i.e. FLY THE AIRCRAFT. This is the default response to any emergency or non-normal situation when a pilot is unclear as to what he/she should do next. And yes, it is a trainable response.

Performing these actions is no more difficult than executing the procedures for an engine fire/failure at V1, and we should not expect any less from a trained and competent commercial flight crew.
With respect-

You were the only pilot that responded to what "would you do" that maintained the flying pilot position. You gave very little tasks to the non flying pilot and you even did not acknowledge the input that they would have given you. Your feed back was of a one man crew.

Both others that replied handed over to the FO to fly, I expect as they had the accurate instruments not just air speed but pitch - the pilots pitch was incorrect!

Again the pilots pitch was incorrect.
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Old 4th May 2019, 13:40
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I recall a mention of the electrical motor running while clutches changed the drive from one authority to another. Is the stopping of the wheel reliant on a clutch slipping? It seems from this thread that the smaller diameter wheel might be a bit of a challenge.

I asked before, but does anyone know how long the motor runs on for? I find it hard to believe it is powered down after every single pulse of the thumb switches, so I assume a lag in the power-down.
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Old 4th May 2019, 13:55
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Originally Posted by Loose rivets
I recall a mention of the electrical motor running while clutches changed the drive from one authority to another. Is the stopping of the wheel reliant on a clutch slipping? It seems from this thread that the smaller diameter wheel might be a bit of a challenge.

I asked before, but does anyone know how long the motor runs on for? I find it hard to believe it is powered down after every single pulse of the thumb switches, so I assume a lag in the power-down.
is a brushless motor, therefore it will be powered on and off for every blip. Practically not lag
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Old 4th May 2019, 14:14
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Originally Posted by 737 Driver
Performing these actions is no more difficult than executing the procedures for an engine fire/failure at V1, and we should not expect any less from a trained and competent commercial flight crew.
Ordinarily I would agree, however, the problem here is that there was a fundamental SA failure in the process of all of these events.

In the flight prior to JT610, the crew did not initially comprehend what was happening, perception was initially missing. The crew did eventually recover from that state when there was intervention by the 3rd flight deck person drawing attention to the trim behaviour. SA-1 Perception Failure. Thereafter the crew went for a 2 hour transit with the stick shaker running in the background...

On JT610, the crew had an SA-1 Perception failure to start with as well, and arguably detected the uncommanded stab motion and thereafter had an SA-2 Comprehension failure, which occurred with the handover to the FO of the aircraft while the Capt commenced further investigation. The Captains handover resulted in the effective termination of intervention from corrective trim input by the FO. Arguably there was an SA-3 type failure at the same time, as the Capt did not project forward the implications of not continuing the intervention of the trim input by MCAS, which led directly to the aircraft being so far out of trim that the dark knowledge of the potential for the trim being defeated without a specific manoeuvre to unload the stab was not realised. The FCOM is underwhelming on the subject, and the Capt ran out of ideas, time, altitude and elevator authority promptly.

ET had some information provided per the EAD, however, the crew had SA-2 failure once again.

Training of runaway stab is not a common item, and training for severe out of trim cases is effectively non-existant, and the FCOM hardly suggests that the matter may end up being critical for recovery time/altitude. If the crews are to be expected to respond appropriately, then sufficient knowledge and training is necessary so that the crew can make a decision based on recognition (RPDM) or if time permits, by analysis. As the crew were still ill informed that control loss was quite possible, and that a recovery would need a procedure that was not meaningfully described and not trained, it is difficult to shoot the messenger, the crew in question.

The SA failures that occurred here occurred in a period of dynamic operations and with high levels of stress on the decision makers. The truth is that people will respond differently with the set of cues that were in play on these occasions, and training to improve the likelihood of a desirable outcome is necessary. Keeping pertinent information from the flight crew was unhelpful, and the FCTM discussion on out of trim events fails to indicate the criticality of the situation, one that raises questions on the basis of certification of the aircraft in the first place.

The crew did try to fly the plane, they didn't recognise the problem, they didn't comprehend what the situation was promptly, and when breaking the manual trim process they did not project the state forward as a result of that action, due to inadequate information and training. Were they flying the plane? they were, but they didn't know they had brought a knife to a gun fight.

The FCTM is a bland understatement of a potentially catastrophic situation.
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Old 4th May 2019, 14:27
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Originally Posted by 737 Driver
Again, no evidence from either of these accidents or from historical data that the electric stab trim motor could stall under load. The matter of the electric trim inhibition discussed in the link above is a completely separate issue. That inhibition prevents main electric trimming (pilot actuated) into a certain region of forward trim, but it does not prevent the use of electric trim to move out of that region.

All this being said, one of the causal factors of these accidents is that the pilots let the aircraft so far out of trim in the first place. It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb - if he had chosen to use it.
"No evidence" is a commonly used phrase used to justify all manner of absurdity (usually by politicians). The absence of evidence does not rule in or rule out anything.

"It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb" It is not absolutely clear at all. The FDR does not track the thumbswitch position as far as I know. Thus, it cannot be said with certainty that there were not additional electric trim up inputs that had no effect. Your assumption seems to be based on the accuracy of Boeings publications. I do not think that any pilot, even a very bad pilot, would not make further electric trim up corrections under the circumstances. For these reasons there remain doubts in my mind. In the case of ET302 it seems the crew reactivated electric trim in desperation... following that action it is difficult to believe that they did not do so to apply constant electric trim up via the thumb switch. It is a puzzle what actually happened, but unless you KNOW what the pilots ACTUALLY did it is mere speculation rather than being "absolutely clear".
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