Originally Posted by
FE Hoppy
I'm not sure how you know that they found all airspeed information gone. There is no indication in the report that the airspeed information was false at any point. Only that for a minute the standby didn't agree with the PFD. I also don't see and indication of a "plethora of warnings".
Hi.
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).
...
Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight.
At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".
All of this is consistent with loss of speed information to the computers (and the flight deck instruments) due to iced-up pitot tubes, and it would appear that the PNF correctly diagnosed this in a little over 10 seconds. The plethora of warnings came after whatever caused the pitch-up and stall condition.
Originally Posted by
peplum
40° AoA, read a such value and i guaranty the guy would have push all his weight on the stick ..
Then why didn't the Birgenair Captain in his 757 do just that in the same situation? This is where the psychological/human factors aspect comes in to play.
Originally Posted by
bearfoil
From three years ago, I have said pretty much the same thing, and after your last post I admitted to that very thing. The problem aisi, is the interface twixt a/c and PF's caress.
And the point I'm making is that the aircraft is, by design, doing exactly as the pilot commands. At this point there is no "interface" as such - the computers are simply doing everything they can to pass the pilot's commands along to the control surfaces.
Anyway - I *really must* leave it there!