cargun
Please get this straight - there was no problem with the autopilot. The system we are concerned with is the autothrottle which is separate. The misreading radalt sent a signal to the autothrottle to retard at an inappropriate time.
I repeat what I said on a previous post. Neither the autothrottle nor the radalt were important in what the crew were doing, namely a single autopilot approach to cat 1 minima. The only time the radalt is of vital importance is during a dual autopilot approach and autoland. Boeing have made it clear that, in that case, a malfunctioning radalt will disconnect the autopilot, thus telling you that you cannot continue with the cat3 approach -go around or continue with a manually flown or single autopilot cat1 approach. I also repeat that the autothrottle is not required for a cat3 approach
I suggest that Boeing do not regard either the radalt or autothrottle to be of sufficient importance as to have an endless system of fail safe devices attached to them - they do not have that much relevance to the safety of the aircraft. Maybe they will now reconsider but personally I do not see the point. It would be a pain if a simple thing like a faulty radalt stopped you using the autopilot.