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Old 29th May 2011, 14:47
  #559 (permalink)  
bearfoil
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Hyperveloce

Very welcome post. Well framed, the challenge to the PF (PNF).

- 13° THS nose up angle: were the pilots informed of this ? If so, a manual trimming back to lower angles would have been their only hope then ? (related SOP ?)
This is the salient concern? With a heavy tail and that large slab forcing down the aft hull, it is disturbing to consider the obstacles to regaining level flight.


- altitude/vertical speed monitoring: the 1st response to the 1st stall alarms was to pitch up/climb (manoeuvre d'urgence ?), then pitch down orders reduced the VS and stabilized the altitude around FL370 (waiting for the CPT). Latter, the CVR shows that crew was aware that the AC was closing FL100, but no early mention (in the last BEA release) of a rapid descent rate (VS).
I think the first two warnings of Stall were transient and not perceived as reliable, after all, the a/c had 0.80-0.82 M, and had response (Pull, Roll Left)? This also occurred prior to loss of speeds reads.

At the top of climb, an AoA of 4 degrees was established, consider this may have been the best obtainable (PF: "Why?"). In arresting the climb, the a/c may have already begun its Stall, with 13 degrees NU (THS), did the crew realize this? 4 degrees AoA, but a Pitch of something much greater? Was sufficient energy available to climb in less than aerodynamic fashion? If the Pilot, absent complete cueing, was lulled into thinking his airframe was behaving normally, the sudden loss of positive g would be alarming, and he may have reduced power to drop the nose, thinking it was the engines maintaining an improper AoA? With full Trim Tanks and a THS at near full NU, did the door slam shut? Can we eliminate a cg moving aft due to loading problems?

Last edited by bearfoil; 29th May 2011 at 15:18.