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Old 05-15-2019, 12:52 PM
  #625  
Singlecoil
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Joined APC: Jan 2010
Position: Supine
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Originally Posted by pangolin View Post
The repeated erroneous application of nose down trim by the automated system - with automation disconnected - that is the problem.

Several have now flown the profile and have only successfully recovered by using the porpoise technique. This technique has been in the manual but has not been taught for decades. Training. Training. Training. MCAS implications with AOA failure were never considered properly. It didn’t auto trim once. In fact the first application was imperceptible. Humans were distracted be erroneous airspeed indications and alarms. MCAS snuck up on them and killed them. I’m sure had they turned the cut off switches back on - retrimmed then turned them off they would have been fine. There wasn’t time by the time they gave up on an impossible to move stab. Yes reducing power could have helped but speed at their attitude would have taken a long time to reduce to a level where the stab could be moved manually. A crew, expecting this exact failure and focusing only on it, expecting it, could only recover using the porpoise technique unloading the stab. If the airplane was an NG with the same AOA failure this would not have happened. MCAS killed them. Not inexperience.
Maybe we should be calling it the "reeling in a big fish" technique instead of the porpoise technique. Just like reeling in a fish, you have to give it some slack to reel in.
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