Originally Posted by
MurphyWasRight 
Why would pilots in a severe AND trim crisis merely blip the switches?
Is there any possibility that the extreme column forces could have interfered with the switches, either mechanically (including wiring etc) or biomechanically.?
By biomechanically I mean could the hand position and forces make the pilot believe he was pressing the switches when in fact he was not?
The FDR shows a 'bunt' with significant g-force due to the final MCAS stabiliser nose down trim. Until that point the trim was stable, so they may not have seen the need for (or possibility of) nose up trim. They may have severely underestimated the force of the nose down trim at high airspeed, compared to the earlier MCAS activation. Within 10 seconds they were experiencing negative 2g and 40 degrees nose down pitch on the FDR, so moving arms may have been impossible. During that time the aft forces on the yoke reached extreme values, and it is probably impossible to pull and trim at the same time. Hope that makes sense.
The 2 blips occurred before the final MCAS action, in fact likely triggered it so the extreme final G load is not a factor. They were flying but with (great?) difficulty before then.
Not sure 3 units AND (from trace) while 'stable' is not correct. From the report it appears they tried and failed to use manual trim wheel after cutout and then (last ditch option) re-enabled it to attempt electrical trim.
Gets back to the question of why 2 short blips instead of continuous until collum force approaches neutral?