Dozy (cc Old Carthusian)
Re: Attitude and "climb".
Dozy, The Nose was actually Low by four degrees v/v flight path, so no goalposts were injured in the making of this post. The a/c was "climbing" nose low ........-4 degrees. The auto pilot will trip out with a NOSE Down of 9 degrees, so I offer this theory, try it on.
For thirty seconds prior to loss of Auto Pilot, the VS select shows 5000fpm down.
This value would trip the a/p due excessive Nose Down, so it is rejected by the FCM. Select/Reject for thirty seconds. NO ICE. The a/p eventually latches the excess (+9) value, and trips out at 2:10:05. NO ICE. As the a/p has tripped due to excess control (past limit), the LAW remains in NORMAL. For an additional ten seconds, the a/c is subject to turbulence that duffs the probes, simultaneously. NO ICE. With discrepant normed Speeds, the a/c degrades now into AL2 NO ICE. It is at this point The PNF announces, "We have lost the speeds, Alternate Law..." NO ICE.
For an updraft to lift this a/c (at the recorded rate) is remarkable. It also screws with the AoA vanes. As the Pitch decreases, the vanes read increasingly higher. PITCH at this point is not the a/c's problem, but AoA is. This is why the a/c initially did not "climb" with PF's aft pulled stick. The elevators were trying to catch up with the airstream, for the better part of ten seconds.
At the point that the elevators got back into the "loop" the climb was already breathtaking, and virtually unnoticed in the cockpit.
Were they in the cell? I believe they were......
EG: Can an aircraft climb rapidly with a Pitch displayed as 'Normal'?
Boy Howdy.
Last edited by Lyman; 26th November 2011 at 16:44.