Originally Posted by
BOAC
- do I take it that you are saying that the 2001 incident was caused by alpha reaching alpha-prot during an over-speed event, then?
I don't think anyone is suggesting that.
Transient overspeed in turbulence prompted the crew to close the throttles.
As speed reduced, turbulence then caused transient increase of alpha to exceed alpha-prot (or the predicted trend to exceed it), this engaged the alpha flight mode such that the neutral sidestick would command alpha-prot (and fully back, alpha-max).
If this is activated by a transient high alpha value, then when that transient effect goes away, you will get a climb. Alpha-floor then probably kicks in to increase the thrust after the pitch up.
- I would suggest that a far better solution would have been to have it NOT activate in the first place?
Ah, but under what circumstances ? Like all safety engineering, in some situations this feature will do the wrong thing (in others it can save you). Sometimes the only survivors are those thrown clear, sometimes it's only those who are belted in - so should we have seatbelts or not ?
Maybe this law should never activate in turbulence in cruise, but on the other hand if it
had activated on 447 (which it didn't because normal law had been lost) then it would probably have avoided the stall. Or consider if the A340 crew in this case had been the ones to get "climb climb..." from TCAS