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Old 27th Apr 2019, 16:49
  #4448 (permalink)  
GordonR_Cape
 
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 58
Posts: 419
Originally Posted by Chu Chu View Post
I find it fascinating to watch highly qualified and experienced folks take nearly opposite views of the crews’ and Boeing’s respective contributions to the accidents.

I wonder if folks might get closer to consensus if the judged the crews based on what did happen, and Boeing on what could have happened. As SLF, I have to accept that the chaos in the cockpit would have been beyond anything I’m capable of imagining. But I’m still skeptical that a crew trapped in a tug-of-war with the control column shouldn’t have worked out that they should apply nose-up trim – and keep applying it until things got better or it became completely obvious that it wasn’t working.

At the same time, I’m assuming that the AOA probe failure could have happened in IMC. At least I haven’t seen anyone explain why it couldn’t. It seems perfectly reasonable that a crew faced with a stick shaker for no obvious reason and a display showing the horizon rising above the flight path for no obvious reason might hesitate before making major nose-up control and pitch inputs. And it sounds like it could have become too late pretty quickly.

Am I missing something?
I raised the possibility of faulty AOA and MCAS activation during night IMC conditions many pages ago, but there were no bites to my suggestion. If you throw in somatogravic illusion, the outcome could only have been more difficult than the two (three) actual cases that occurred in daytime VMC conditions. Juggling flight controls, instrument displays and spatial orientation at once would a real handful.

You comment raises a broader issue: With hindsight we know that both aircraft were flyable, with the right sequence of control inputs. At the time the pilots could not have known this for sure, and may have wasted energy on many mental scenarios, most of which did not lead to the small number of escape steps. They did not know for certain if there was any kind of mechanical malfunction (parts of the horizontal stabiliser or elevator fell off, control systems jammed), computer gone rogue (we know the cutoff switches are supposed to work, but are you really sure). In addition they might conceivably avoid doing things that might make the situation worse, or provoke the computer systems into more nose-down trim?

As several personal anecdotes have reminded us, when things go seriously wrong, rational thought sometimes goes right out the window. My understanding is that passenger jet pilots do not wake up in the morning expecting to face imminent death. The training process does not emphasise this kind of life or death situation, and the selection process does not specifically weed out those that would fail to meet test-pilot or astronaut standards.
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