Maverick ,I locked onto the localizer once at>300kts in a 330.It was quite a sharp turn-on but it coped with it.If ATC give you a bad turn ie through the loc the afs stays in loc* until it recaptures from the other side.The A300 is quite susceptable to loc deviations due to ac on the rwy and departing-Airbus came up with a localizer inertial smoother to sort it out but my company didn't buy it.The quality of the afs has got better as computer technology has improved.On a day to day basis it is impossible to know what mod standard is in the box under your feet you just use it sensibly.
