It was an interesting decision by the crew to leave the autopilot engaged as the speed decayed.
Perhaps there was a good reason for this. Perhaps they were understandably so preoccupied with trying to work out why there was no response from the thrust levers, that the speed decay went unnoticed.
However, the reason why the autopilot allowed the speed to decay was not because it was attempting to fly at the best speed for the situation presented to the crew. It was because it was attempting to maintain a glideslope that it was commanded to follow. Unfortunately, a decaying speed from about 140 knots at 750 feet to 108 knots at 200 feet, resulted in a severely degraded flight path angle.
If the autopilot/authorottle is not performing what it is commanded to do, (in this case maintaining the commanded speed), then it is best to disconnect, and correct the situation manually.
In this instance, as the speed started to decay, an autopilot disconnect followed by flying at a speed of between VREF and VREF minus 10 would, quite probably, have resulted in a different outcome, and a more controlled landing.
Last edited by Wornout Rubber; 25th February 2008 at 08:05.