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by WalterBright
2012 days ago
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Neither crash was within a few seconds. The EA crew fought it for 5 minutes, the LA crew 25 minutes. -- Aviation Week, Sep 1, 2019 As for being an emergency, yes it was, and dealing with emergencies is most of pilot training. Dealing with runaway trim (which is how this failure exhibited) is part of that training. The Emergency Airworthiness Directive reiterated what the procedure was for runaway trim. Runaway trim is so serious that it is a "memory item" meaning the pilots know how to deal with it without needing to consult a checklist. While runaway trim should never happen, it is reasonable to expect the pilots to deal with it properly. |
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That's not what I said.
If you don't take mitigating actions within a time window of a few seconds, you are locked into an unrecoverable situation - however long you might fight it afterwards.
Specifically - the trim wheel is too stiff to correct if the stabilizer is loaded, so if the MCAS is allowed to wind the stabilizer to its extreme position, the pilot must - after disabling the MCAS (and therefore also the electric trim) - unload the control column to correct the situation, which will send the aircraft straight into the ground. Hence the undulations seen in the flight paths of the crashed aircraft.
The MCAS was designed under the assumption that pilots would respond to unexpected activation within 3 seconds:
https://www.seattletimes.com/seattle-news/times-watchdog/the...