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Old 11th Mar 2020, 12:00
  #23 (permalink)  
FullWings
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
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I agree with alf that you have to take a holistic approach to see why these accidents happened. If you look for “holes in the cheese”, they appear right from the start in a progression through design, testing, certification, documentation, training and instruction. The MAX congressional report backs much of this up.

There is a world of difference between a continuous trim runaway at altitude and level flight in the sim, knowing it’s going to happen, and something that presents without warning as UAS and/or stall combined with intermittent trim inputs at a phase of flight where intermittent trim inputs are expected and the ground is not far away. Add sensory overload to a complicated decision tree to navigate and it is no wonder that things went badly. Boeing internally estimated that you had <10s to correct the problem before it became possibly unrecoverable - this was before any of the crashes happened.

Yes, it could have been handled better but this was a multiple failure scenario at a critical stage of flight; we also don’t know if the MAX or other variants can be manually trimmed at Vmo with the stab a long way out-of-trim forward (the roller coaster doesn’t work at low altitude).
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