PPRuNe Forums - View Single Post - AF 447 Thread No. 7
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Old 19th Nov 2011, 10:31
  #406 (permalink)  
CONF iture
 
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Originally Posted by IF789
I don't think stopping autotrim would have affected this accident. I know you've argued that had the nose gone down they'd have diagnosed the stall, but I'm not so sure. When the a/c did pitch down in stall what was the reaction ? Pull-up, hard. If you're already prepared and briefed for stall in the sim, the nose drop is going to be obvious, but if you think the a/c isn't responding right (which looks like an issue in roll at least even before the stall) and you're pulling back and the a/c suddenly drops the nose, what will you do ?
To trim up in such circumstance must be a pilot's call, not one for the automation.
Let the crew make such a deadly mistake, don't do it for him please.

Trim / AutoTrim: oh yes.
Now we would need to evaluate both item separately ...

But what is the typical problem with trim, what's its MO when it kills ? Looks to me like it's trim-up before stall, autos drop out, trim not managed by crew then contributing to the upset and/or preventing the recovery. Exactly the opposite of 447 - which looks like the odd one out.
Because trimming to the limit of the AP like in AMS or LGW is not a better idea - AP should give back control before reaching such extreme because autotrim itself should not be allowed to go that far.

I note that limits for the 320 electric trim and manual trim are different.
It is apparently not the case for the 330 ?
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