Originally Posted by
yanrair
my apologies. Misunderstanding. I was just referring to 737 needing AND trim all the time during acceleration.
all you say is correct. The NNP for runaway stab. Is predicated on staying ahead of trim requirements. To avoid the last ditch heave up , and unload- TRIM TRIM TRIM NU routine. Use trim switches NU until stab back in trim - not blip blip , but major NU input over several seconds. STAB OFF. TRIM Manually thereafter. In runaway stab in previous variants by the time you notice, the stab. will be a couple of divisions AND. Or more and requires a sustained ANU input.
Here is what I was referring to (published by satguru) :
Recent training handbook also recommend using the speed for which the aircraft is trimmed, i.e. AND => increasing speed
In the case of ET 302, it is clear that INCREASING speed had no chance of success and lead to loosing control.
REDUCING speed would have caused a pitch down moment induced by static stability and by reduced thrust, which AMHO could have been counteracted by elevator, until the moment when the aerodynamic loads would have been alleviated enough to permit manual trimming. If manuel trim were still jammed, aft forces required on the column to maintain level flight would have been lower (due to logic of feel and centering system) with no risk of elevator blowback anymore.