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Old 31st May 2011, 05:01
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mm43
 
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JD-EE
if it got them totally confused it's a software specification design problem.
Undoubtedly! It would appear that no-one anticipated an approach to a stall that wouldn't under normal circumstances be dealt with correctly. In this case it wasn't, and degradation of air-data was such that the SW operated in a negative sense, i.e. letting them think they were about to stall again, whereas if they had persisted they would have gone through the warning with a chance of recovery.

As takata has rightly pointed out, IAS greater than 60KTS AND/OR AoA less than 30 degrees are required to prevent the Abnormal Law activating. It is while in this AND/OR regime that a very clear warning needs to be given that the aircraft is stalled. IAS is useful, and AoA is useful, and it would be preferable to know each rather than being left in the dark because one or the other, or both wasn't deemed valid.

Last edited by mm43; 31st May 2011 at 05:12. Reason: changed IAS less to greater
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