Originally Posted by
atakacs
Quick question: on what basis does the BEA reports that the speed measurement became valid again at 2:12:21 ?
The reply to that question is probably given in that part of the BEA report:
Note: When the measured speeds are below 60 kt, the measured angle of attack values are considered
invalid and are not taken into account by the systems. When they are below 30 kt, the speed values
themselves are considered invalid.
My explanation:
After the AoA exceeded 40° the airstream to the pitot probably totally collapsed/stalled, leading to an IAS below 30kts.
After reducing AoA by the PF the airstream probably partly unstalled and IAS in the pitot exceeded that threshold again.
That is what probably led to the confusing result of pitch-down leading to the stall warning going off again.
IMHO that is not a good solution. AI should seriously rethink that.
The only strange thing is that speed being declared invalid and stall warning stopping suppoesedly happened at the same time as the stall warning should disappear below 60kts and the speed indication below 30kts.
/Edit: parallel post to MurphyWasRight