PJ2
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).
Much earlier on the other main AF447 thread, there was a posting about an available Airbus system (BUSS-BackUp Speed Scale),(an available option in purchasing the aircraft) that inferred airspeed using AOA and a computer performance model of the aircraft (Post 4041). I'm not sure that even that approach is adequate. Suppose a hail encounter "modified the aircraft" a bit, e.g. removed the radome. Would your AOA sensors then be valid?
If AOA is ever presented in an airliner, I hope there is not too much computer mediation of the display. You don't want a damaged or defective probe or vane causing an accident ( e.g. A310 in Africa), so redundant sources are desirable, but computed AOA involving airspeed derived validation scares me. I've flown a lot with single source AOA indicators and have found them to be reliable and simple to interpret. You do have to pre-flight the probes/vanes but it is just a visual check. The info could be available on your PFD with minimal work, and a few flights/simulator sessions would give you the big picture of how it does its job.
Has anyone ever worked out how many damaged/destroyed airliners might have potentially been saved by providing the crew better AOA awareness? Is that stall warning after takeoff real or bogus? Might be an interesting study.
P.S. Didn't the L1011 have AOA indicators? How did that work out?
Machinbird
Last edited by Machinbird; 22nd March 2010 at 05:10.