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Old 9th Mar 2009, 18:23
  #1944 (permalink)  
MU3001A
 
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Rainboe:

It (the autoland function) is a default. Except you are not allowed to do this (on one autopilot).
So a minor element of an uncertified configuration of the automation malfunctioned triggering an uncommanded mode the crew were not made aware of - given the TL's were probably at idle anyway in the early part of the descent on G/S, except by a subtle change in mode annunciation that could be easily missed.

I don't excuse the crews apparent inattention to airspeed, thrust setting or mode annunciation during the approach. But neither should we excuse the triggering effect caused by the malfunction of a relatively minor piece of equipment, nor its effect on recovery from the ensuing stall. All as a result of the way Boeing chose to wire the equipment to provide an undocumented and uncertified configuration of the automation. A configuration which crews are not normally trained on and judging by many of the comments from NG qualified pilots on this thread, were until this accident largely unaware of.

I doubt the investigative or regulatory agencies will either.
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