Ah yes, Nigel, then why did the plane transition from Mach 0.8 into a stall merely because the reported airspeed became incoherent and went to a very low number?
Originally Posted by from the BEA report
From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS).
If it is stall warning is solely vane controlled methinks something went REALLY sour in weather system for that to happen. simultaneously something makes the air speed indicators drop AND the angle of attack to appear to change significantly.
Now, speed and altitude MUST figure into the stall warning as the stall speed at 1000' and 250 knots and a 2 degree AoA is not quite the same as at 35000' and a 3 degree AoA (picking numbers of of my nose not for exactitude.)
As a lay person who does understand "systems" concepts this stall warning without the plane changing velocity, moments after the AP and AT cut out and the air speed drops to 60 knots MUST have some screwy roots somewhere in the system. Could the plane have hit a weather phenomenon that could mess up the pitot tubes and simultaneously subject the plane to a high speed down draft strong enough to move the AoA indicator into a stall configuration? If this can happen would there be any way to save the plane? If it speeds up out of the stall and comes out the other side into the matching up draft things could get exciting in a Mach sort of way, couldn't it?
If it can, would it vindicate my smart assed remark, "Don't just do something, sit there!" (Meaning of course, think first. Think THEN Avigate, Navigate, and Communicate.)
What sets of events could that report from 2 h 10 min 05 really mean?