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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 24th Sep 2019, 00:30
  #2561 (permalink)  
 
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Humble answer: The pilot keeps inputing nose up trim to counter the undesired nose down trim. At some point when the pilot gets tired of repeatedly putting in nose up trim, the pilot deactivates the electric stab trim system and reverts to manual trim.
Which would be fine if the manual trim was actually effective throughout the flight envelope but it seems it may not be, for practical purposes...
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Old 24th Sep 2019, 00:31
  #2562 (permalink)  
 
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A technical clarification is in order. At no time did the automation (i.e. MCAS) "override" pilot inputs.
Well pilots had been trained and on all previous to MAX, when pilot pulled( or pushed ) on yoke in opposition to trim direction, trim STOPPED.

But that never happened, since the appropriate switches / sensors had been bypassed or disabled due to incorporation of MCAS.

So splitting technical hairs - did MCAS override pilot input ??
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Old 24th Sep 2019, 00:41
  #2563 (permalink)  
 
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Originally Posted by FullWings View Post
Which would be fine if the manual trim was actually effective throughout the flight envelope but it seems it may not be, for practical purposes...
The underlying presumption in this particular case is that the pilots could have used the fully functioning Main Electric Trim to return the aircraft to somewhere close to an in-trim state before turning off the electrics. Yes, we know that didn't happen, and the reason why that didn't happen is an important discussion. However, we need to first recognize that the capability was actually there.
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Old 24th Sep 2019, 01:01
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That is asking a lot of Joe Pilot.
He's been taught to trust the instruments which are now driving him into the ground, for reasons he does not understand or know about. Plus his inputs are reversed at much higher speed by automatics he does not know exist.
I'd hate to be subject to that test, because I'm sure I'd fail it.
Where that leaves Boeing is beyond my competence, but I cannot see the regulators remaining oblivious.
Imho, the MAX is dead.
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Old 24th Sep 2019, 01:02
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Originally Posted by jdawg View Post
Just hate to see others here say the pilots should have simply established a pitch and set a thrust setting.
That's not what started this subthread.

The point was AoA indicator is not needed. That's why it was an option. It's not required by the FAA/EASA/etc.

You fly attitude and power not AoA.
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Old 24th Sep 2019, 01:10
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Originally Posted by JPJP View Post
This is what the alert looks like on the MAX PFD. Itís tiny.



Shows how unimportant it was considered and why there was no rush to push a fix.
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Old 24th Sep 2019, 01:18
  #2567 (permalink)  
 
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Originally Posted by ST Dog View Post
That's not what started this subthread.

The point was AoA indicator is not needed. That's why it was an option. It's not required by the FAA/EASA/etc.

You fly attitude and power not AoA.
It was also not my intention to imply "the pilots should/could have just flown attitude and thrust" . Rather I was trying to have a discussion around the need for there to be an understanding that the automation can (and did in this and other situations) loose situational awareness , in such case it should not be raising any situational alarms or (as in this case) taking any action. In this case the FMC did know it was foo-bar but did not have a programmed response of shutting down all situational processes and alarms to a fail safe state. It could and should have!
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Old 24th Sep 2019, 01:51
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Originally Posted by etudiant View Post
That is asking a lot of Joe Pilot.
I agree that it would be a lot to ask of any pilot who had not been trained for a malfunction like this, but it is not inherently an impossible situation with the proper training. I think the germane question is whether changes need to be made to the current pilot training regimen. I can tell you from personal experience that until the MAX accidents, training for anything that looked like runaway stab trim had been spotty to non-existent at my airline (a reasonably well-regarded "developed world" operation). I suspect we were not the only ones who neglected this training for far too long.
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Old 24th Sep 2019, 02:26
  #2569 (permalink)  
 
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Compensation being offered by Boeing over family losses is a pittance USA wise, I would have expected at least a naught on the end.

https://www.bbc.co.uk/news/business-49803068
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Old 24th Sep 2019, 02:50
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tomaski
I agree that it would be a lot to ask of any pilot who had not been trained for a malfunction like this, but it is not inherently an impossible situation with the proper training. I think the germane question is whether changes need to be made to the current pilot training regimen. I can tell you from personal experience that until the MAX accidents, training for anything that looked like runaway stab trim had been spotty to non-existent at my airline (a reasonably well-regarded "developed world" operation). I suspect we were not the only ones who neglected this training for far too long.
Lets see - Assuming pilot realized he had to use trim switch to get near level trim BEFORE hitting kill switch - how long did he have ? Seems to me he had at best 5 seconds - now with a typical call - response - action - how much ' slack ' was available ??
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Old 24th Sep 2019, 04:11
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Originally Posted by ST Dog View Post
That's not what started this subthread.

The point was AoA indicator is not needed. That's why it was an option. It's not required by the FAA/EASA/etc.

You fly attitude and power not AoA.
So we agree AoA is not necessary but my question to you remains. How do you fly attitude in a loss of pitch control situation? Just wait for the pitch control to return on its own?
You don't understand the severity nor scope of the Max crisis. Ironically your strategy is exactly what the crews did, simply tried to fly an attitude. It didn't work.
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Old 24th Sep 2019, 10:11
  #2572 (permalink)  
 
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Originally Posted by JPJP View Post

This is what the alert looks like on the MAX PFD. Itís tiny.
It looks more like a secondary indication than an alert.
The non-certified aviation seems to have a better grasp of human factor and ergonomics.
This is how a better thought out display could have looked like, with an alert in the direct field of vision of the pilot.
And an AOA indication at a useful place.





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Old 24th Sep 2019, 10:42
  #2573 (permalink)  
 
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How do you fly attitude in a loss of pitch control situation?
There was no "loss of pitch control". That is clear as the aircraft continued to fly until a hand over of control in the case of one flight. The elevator simply became "heavier" as MCAS wound in forward trim. Any pilot used to hand flying would then instinctively wind in back trim to lighten the control load. As Tomaski said above, why they did not do this is a germane point.
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Old 24th Sep 2019, 11:56
  #2574 (permalink)  
 
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What are they doing all day!? Is it so difficult to certify an aircraft again! Every day has 24 hours how long can it take!
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Old 24th Sep 2019, 13:00
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Originally Posted by babemagnet View Post
What are they doing all day!? Is it so difficult to certify an aircraft again! Every day has 24 hours how long can it take!
They are re-examining the recertification process. They'll be done when everyone is satisfied that they have it right. How long will that take?
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Old 24th Sep 2019, 13:14
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Thumbs up

I like! I like very, very much!

Originally Posted by Fly Aiprt View Post
It looks more like a secondary indication than an alert.
The non-certified aviation seems to have a better grasp of human factor and ergonomics.
This is how a better thought out display could have looked like, with an alert in the direct field of vision of the pilot.
And an AOA indication at a useful place.




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Old 24th Sep 2019, 13:17
  #2577 (permalink)  
 
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Originally Posted by Fly Aiprt View Post
It looks more like a secondary indication than an alert.
At the time the indication was designed, presumably Boeing considered it to be purely informational.

Rather than a warning that there was a risk of the aircraft becoming uncontrollable and killing everyone on board ...
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Old 24th Sep 2019, 13:34
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Originally Posted by DaveReidUK View Post
At the time the indication was designed, presumably Boeing considered it to be purely informational.

Rather than a warning that there was a risk of the aircraft becoming uncontrollable and killing everyone on board ...
A condition that kills you in 3 seconds would justify a display and a circuit breaker.

I have no doubt that ten years from now an AoA/Mcas related fault will kill some poor bastards again.

Edmund
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Old 24th Sep 2019, 14:15
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Originally Posted by Grebe View Post
tomaski

Lets see - Assuming pilot realized he had to use trim switch to get near level trim BEFORE hitting kill switch - how long did he have ? Seems to me he had at best 5 seconds - now with a typical call - response - action - how much ' slack ' was available ??
Once the pilot is actively and aggressively engaged with using the Main Electric Trim, they have as long as they need. By design, MCAS would pause for 5 seconds every time the Main Electric Trim (yoke switch) was used, and there is no limit to how long the Main Electric Trim could be run at any one time. In theory, one long nose up trim input to put the trim back in place, then a series of short trim inputs every 5 seconds or so. The pilot could literally do this as long as they wanted until they either 1) ran the Runaway Stab Trim procedure to conclusion, or 2) slowed down to less than 250 KIAS (if not already there) and extended the flaps. Again, not an impossible situation to manage with proper information and training - and that is exactly what was missing.

If pilots were never properly trained to handle critical emergencies like engine failures and windshear during takeoff, we would not be surprised to see accidents when these events occur. But we do train for them, pretty much every single time we go through a sim session. How often were the accident pilots exposed to a Runaway Stab Trim scenario? I haven't seen one in years, though I expect that will probably be changing.

Yes, MCAS was a crap system and never should have made it past certification. Not informing crews of its existence was borderline criminal. That doesn't mean it was not possible for pilots to have been exposed to the type of training that would have allowed them to survive this malfunction. (And before anyone jumps on this bandwagon, I am NOT blaming the pilots. The pilots do not create the procedures, the training syllabus, or the corporate culture that gives a short-shrift to safety. However, they are products of all the above).

Specifically as to training and general operations, here are some areas that need attention:
  • Automation policy. By their very nature, some malfunctions strip away the automation. The pilots need to be able to operate without automation/normal law AND respond to a critical malfunction. That only comes from regular practice flying without these aids. If it is an airline's policy that pilots operate at the highest levels of automation all the time, we should not be surprised when they become task-saturated when the automation is no longer there to assist them.
  • Overly-scripted training. Pretty much every where, training has become a series of scripted malfunctions that are known in advance. Multiple malfunctions are not presented. There is little, if any, use of surprise or ambiguity. Real life does not go by script, nor is there any natural law prohibiting multiple or ambiguous malfunctions.
  • Over-reliance on procedure, not enough big picture. Procedures are a pilot's bread and butter, and should not be disregarded lightly. However, every manufacturer will also state that they cannot devise a procedure for every situation. In certain situations pilots need to recognize when a situation does not fit a specific procedure (rather than going heads down looking for a procedure that does not exist), and rely on basic airmanship and systems knowledge to do what is necessary to stabilize the situation. If this concept is not instilled into flight crews, then they be poorly equipped to navigate the unexpected.
A thorough accident investigation provides an opportunity to identify and correct deficiencies throughout the entire chain of events. Yes, Boeing is responsible for the most egregious lapse in the chain, but there are other issues at work here and ought to be addressed as well. The problem, of course, is that the additional training outlined above will require an investment of time and money, and airlines are extremely cost-driven enterprises. They will be very reluctant to make this investment without outside pressure.

Last edited by Tomaski; 24th Sep 2019 at 14:39.
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Old 24th Sep 2019, 14:36
  #2580 (permalink)  
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Originally Posted by Tomaski View Post
Yes, MCAS was a crap system and never should have made it past certification. Not informing crews of its existence was borderline criminal. That doesn't mean it was not possible for pilots to have been exposed to the type of training that would have allowed them to survive this malfunction.
Sure, it could be trained, but there would be no need for such training if the system didn't do that. Presumably, going forward and assuming that the MAX gets back in the air, it won't do that -- a much better situation.

Edit: Also, there is some question about the likelihood of pilots promptly recognizing improper MCAS intervention, even if they know about the system. And, in the original version, if you didn't identify the problem and sort it out in 40 seconds, you and your pax were dead. It's OK with me if you want to try to train aircrews for situations like that, but I wouldn't want to bet my life on the results of that training.

Last edited by OldnGrounded; 24th Sep 2019 at 14:48.
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