Machinbird;
It was only my intention to point out that when you really might need such information as AOA, your customary sources of inferring it would not be available. Once the ADIRU outputs are disqualified, the velocity vector information they provide is removed and the aircraft systems have to make do with what is left (which isn't much).
Thank you for your reply. Understand your intention, but while other remarkable developments have occurred the use of AoA in airliners as a primary indication doesn't appear to be widespread perhaps because it just hasn't been a problem. Regarding a survey of accidents, off the top of my head I can recall six accidents in which a stall was involved in the accident sequence; Colgan Q400, Turkish B737, One-Two-Go MD82, Spanair MD82, Empire (FedEx)ATR42, USAirways B737 (Pittsburgh) and possibly AF447. This doesn't include several fatal Bombardier RJ stall accidents caused by contaminated wing surfaces. Of course, no AoA indication is going to assist the crew in the contaminated wing case.
I would like to know what I'm missing about AoA. In my opinion, and I hope HN39 and others will comment, on the surface and except for possibly one accident I don't see the direct availability of AoA to the crew making a difference in these accidents listed above even assuming, obviously, that crews would have been trained to use the indication.
The question and argument here I think is, what does AoA offer that CAS does not. There is the obvious case where 'g'-loading is involved but in considering the accidents described herein the low altitude (around 400') of the Turkish B737 when the secondary stall occurred (I believe due to pitch up from increasing engine thrust) would have made any successful recovery doubtful. It might have made a difference in the USAirways B737 accident near Pittsburgh, providing sufficient information for the crew to "relax" on the elevator just enough to unstall the airplane. That may have been mentioned in the report, I don't know.
BTW the A330 has 3 AoA vanes - Capt., F/O, Stby, with inputs to the three ADIRUs. Not sure you were referring to the A330 present design or to the previous suggestion regarding "
computed AOA involving airspeed derived validation scares me". I agree with you even for a backup system, but just to make clear that the A330 system is sensor-derived although the display of the 'bird' is of course DMC (Display Monitor Computer) driven.
PJ2