From 2:10:08 until impact the a/c was in AL2b. (BEA)
...perhaps sooner, but it was annunciated at :08. And even then, crew did not know which AL....
AL2b latches when none of three ADRs is available.
.....which was immediate, and the reason the THS stopped moving
At no time was a/s available to the crew, from 2:10:08 on.... By definition.
...There was no way for them to get whether subsequent speeds were valid. It took the DFDR to explain it, after they were dead.
Whether or not the a/s was demonstrably "accurate" at any time, the pilots could not have known, by definition.
The THS is inhibited when 3ADRs are unavailable, by design...
.....after it started up again, was the LAW changed? The Protections? The DFDR showed it hadn't. Again, after they were dead.
Yet the THS was moving prior to STALL... Whether the crew knew it was moving or not, they had no reason to want to stop it.
By definition, the a/c was demonstrably in the incorrect flight control LAW when the THS was moving... If it moves, Alpha prot must be available, according to Flight Law. So why stop it? Protection applies.
I was taught never to maneuver with trim, trim is trim, not a flight control....
As the aircraft was dissipating energy rapidly, the THS was not trimming, it was flying the aircraft...Once STALLED, the airstream never allowed valid speeds?
So if the ADRs are never available, the crew have no airspeed, ever, by definition. It is unlikely this was trained, 330 pilots here were unfamiliar with 2b.
At times in the critical path, airspeed was "valid" (BEA).
......excellent, how was the crew to know?
NO, it was not valid, not in any useful way. "vitesse feu".
next, Flight Directors....
The FDs were not turned off, nor was A/P, shouldn't this be part of automatic disconnect, along with Thrust? If leaving them active prevents autoflight, how does leaving them on, help recovery? Especilly when they return intermittently, to resume random modes?
Last edited by Lyman; 6th Oct 2012 at 18:02.