I mentioned a few weeks ago that the aircraft could have levelled off at 11000’. In fact one of the departures has a level off altitude of 11k. (Different Dep to this one though).
FR does actually show a reduction of V/S from around off 10k.
my post was deleted for whatever reason.
Lets run with the A/T malfunction for a moment.
Previous poster said this has never happened in the climb. However, the A/T clutch etc, could fail at anytime. In the climb this would be no big deal until top of climb when the power comes off. At high altitude and assuming M.72 for the cruise, one TL only retards and the other is stuck. The TL will retard to maintain the selected or managed speed. At high altitude this should not present a problem with the Autopilot as the thrust reduction and subsequent yaw would not be great enough to disconnect it. The pilots should have enough time to figure out what is going on.
However at 10000’ the autopilot would not be able to cope, without any intervention from the pilots the aircraft would quickly roll and enter a spiral dive.
What was the trigger that caused the upset, assuming A/T failure?
On this flight the aircraft was actually cleared to FL290, (from YouTube). There should not have been any level off. The only indication is the few seconds at 10900’ for whatever reason. Question? Did the pilots have a selected altitude of 11000’ in the window.