Re:Plane Tests Must Use Average Pilots, NTSB Says After 737 ...
by mlyle on Friday September 27, 2019 @07:12PM
(#21097105)
> MCAS is a badly designed system, but many other stabiliser control failures could cause the aircraft to rapidly lose altitude. The solution is the same in all cases - flip the cutoff switches to disconnect automatic stab control and trim the stabiliser manually using the wheel on the center console.
ET302 tried this-- maybe slightly late, but MCAS is weird/sneaky. Still, it's hard to fault their response at this point.
They were unable to budge the trim wheel because of overspeed. They were barely climbing at Vmo. This left them in a difficult position.
Ideal response would be to reduce power (prevent overspeed), keep climbing at Vmo. During this, try to turn trim wheel. If necessary, once they had sufficient altitude, they could aerodynamically unload and trim. Instead they, for some reason, decided to turn the stabilator trim system back on (whoops 1), and then used it an insufficient amount to get trim to a reasonable place (whoops 2), and then left it on for MCAS to trigger again (whoops 3).
ET302 tried this-- maybe slightly late, but MCAS is weird/sneaky. Still, it's hard to fault their response at this point.
They were unable to budge the trim wheel because of overspeed. They were barely climbing at Vmo. This left them in a difficult position.
Ideal response would be to reduce power (prevent overspeed), keep climbing at Vmo. During this, try to turn trim wheel. If necessary, once they had sufficient altitude, they could aerodynamically unload and trim. Instead they, for some reason, decided to turn the stabilator trim system back on (whoops 1), and then used it an insufficient amount to get trim to a reasonable place (whoops 2), and then left it on for MCAS to trigger again (whoops 3).