Originally Posted by
BOAC
- I am aware of all that, but it does NOT explain why the a/c was pitched by the system towards alpha max from level cruising flight - that is the explanation I am seeking. I can see absolutely no logic in this function.
Can anyone?
If we are still discussing the A340 airprox the only explanation I have is that with A/P off due to overspeed, so flight control in Normal mode, engines put to idle by pilot action to stop the engine cycling. Turbulence caused a predicted AoA measurement above alpha prot and the
High alpha protection triggered to keep the AoA
down to alpha prot. Also possible the initial pitch up triggered "alpha floor" and the subsequent pitch up was in response to the sudden throttle increase?
Further references - first is by mm43?
A340 - A330 Control: Flight & Laws
Aerospace/Aviation: Airbus, thrust levers, thrust system
Only direct relevance to AF447 is that if the pitch up can be caused by an AoA spike we have possibility of a QF72 style (pitch down) uncommanded pitch up if there was a period on Normal before Alt2? I do not believe QF72 event ever explained - two faults one the generation of spurious spiky AoA data, the second the incorrect use of the bad data - they were waiting for further info from AF447 before finalizing report - hardware not identical, but maybe control philosophy?