ASFKAP, indeed the Airbus is certified for Cat 111a approaches on one engine. In fact, the Airbus perefoms everything that a B737 will do one two engines, when the Airbus is on one, except maybe climb at the same rate!
A misconception is that the reason for the back trim is to assure a soft touchdown; it is not, it is to ensure that the aircraft is trimmed for the Go/Around, should it be required.
Also, the Airbus has Auto rudder trim, which the B737 does not have, hence an autoland is allowed on a single engine. On the B737 the pilot would have to constantly adjust the rudder when attempting an autoland. In the last event, the Autolpilot on the Airbus is 'Fail Active' whereas the B737 is fail passive, hence the one is certified for single engine landings on the autolpiot and the other is not.
Just to be contentious, as the point has been raised; Why did the DC-10 crew try to land the aircraft at an airport? Under the heading of; 'Attitude at Impact' I once wrote, in a very minor journal, a short piece querying the attitude of pilots when faced with an emergency for which they are patently not prepared. I am not being critical of those pilots who tried so herocially to land the aircraft, I am simply questioning their motives, their reason behind those decisions.
Sioux city is surrounded by flat, open farm land. The aircraft was controllable, up to a point, in that they could command pitch and lateral changes. Why did they not simply apply these techniques to get the aircraft straight and level, reduce the power and fly gently into the ground? I know our instincts and training are to rreturn to the nearest suitable runway, but why? This argument could also have been applied to the Concorde crash. Why not shut down the remaining engines and crash straight ahead instead of with full power applied to one side of the aircraft, rolling it on its back and, well, crashing?
Happy Landings.