Old 23rd Aug 2019, 00:09
  #1993 (permalink)  
Speed of Sound
Join Date: Jul 2002
Location: Ireland
Posts: 595
Originally Posted by Zeffy View Post

Peter Lemme has posted a deep analysis of the differences between NG and MAX stab trim systems as well as the proposed changes:

​​​​​​Connecting the Dots: From Command to Action
Wow that is some serious analysis! Thanks for posting.

Something which won’t help those arguing ‘pilot error’ is the fact that on the MAX, the previous NG logic where an aft column cutout switch inhibits any ongoing nose down trim is absent. That means that simply following any runaway trim procedure will lose the precious seconds needed to discover that although you are pulling back on the column, the automatic nose down trim is still being activated. If pilots were not informed that MCAS existed I can’t see how they would automatically know that the cut out switch logic had changed.

Not only are seconds lost discovering this but then this is followed by the inevitable “Hold on a minute, that was unexpected. What the hell is going on here?” moment, which not only loses more time but also disturbs the cognitive flow needed to first analyse the problem and then apply a solution.

Too many 737 pilots now know the situation on the MAX for it to be of any statistical use, but early on in this process it would have been interesting to have thrown a number of line pilots into the false MCAS operation/low altitude/climb power situation in the sim, to see exactly how many would analyse the problem and fly out of it and how many would end up flying it into the ground.
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