Originally Posted by
tdracer
Educated guess.................One engine throttle failed to move in response to the autothrottle command at level off..........Aircraft rolled due to the thrust asymmetry, crew caught off-guard by sudden AP disconnect, lost SA, and did all the wrong things.....
If this is what happened then sadly it would have all been displayed in front of them - a big thrust lever and N1 split with one thrust lever stuck at climb thrust while the other reduced to a low setting for levelling off. No autopilot control of the rudder on B737 to compensate for a large engine thrust difference, so the ailerons would have been hard over - again plain for the pilots to see on the yokes.
(When I flew B737, we were told to have hand on thrust levers whenever they were expected to move, e.g. levelling off from a climb.)
The autopilot suddenly dropping out would have been the final straw - the ailerons were being held hard over, but once the autopilot dropped out they would have returned to neutral, and unless correct manual action was taken quickly, the pilots would have been hard pushed to retain control.
Perhaps there should be some sort of alarm that the autopilot is approaching its drop-out point, so crews would know before it actually happens?