So what actually happens if the A/T Arm is left on during final approach and the pilot is using manual thrust? For example if Vref 40 is (say) 130 knots and the pilot crosses the fence exactly on Vref, do the throttles go forward to prevent the aircraft from going below Vref? After all the FCTM allows for a speed range between Vref to Vref minus 5 knots for touch down.
On a similar vein if perchance the aircraft floats with speed bleeding a few knots below Vref during the float - again do the throttles advance just when you don't want them to? And if unrestrained, how much is thrust (N1) is increased. It must be distracting for the PF when he feels the thrust levers opening up under his hand while he is manually controlling them. Seems to me Boeing made a wise decision in advising switching off the ARM mode for manual thrust
