Originally Posted by
Lake1952
One bit of automation logic that might have helped further doom this already confused and disoriented crew was the fact that the stall warnings cut out below a certain IAS, say 80 kts (I forget the exact speed). So here they were with almost no airspeed which silenced the stall warnings, and when one of the pilots correctly lowered the nose causing the IAS to climb above the cutoff value, the stall warning indicators all started their warnings again. This led the crew to believe that their corrective action was causing the stall, and they promptly reversed their action which silenced the warnings. It is entirely possible that had the stall warnings not ceased to warn below that certain airspeed, they would have recognized their situation sooner. And the proper corrective action causing the warnings to reactivate simply confused the situation further.
I think the "cutoff" value was "60 knots", Incorporated so the StallWarn would not activate on the ground. It was determined, at least on thread, that a better trigger would be "weight on wheels", "WOW". Which makes more sense. Stall is not a function of airspeed. Stall is a result of exceeding a critical Angle of Attack. To WIt: 447's velocity through the air at impact was approximately 240 knots... Was she Stalled? ...... Boy Howdy