Originally Posted by
737 Driver
Again, no evidence from either of these accidents or from historical data that the electric stab trim motor could stall under load. The matter of the electric trim inhibition discussed in the link above is a completely separate issue. That inhibition prevents main electric trimming (pilot actuated) into a certain region of forward trim, but it does not prevent the use of electric trim to move out of that region.
All this being said, one of the causal factors of these accidents is that the pilots let the aircraft so far out of trim in the first place. It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb - if he had chosen to use it.
"No evidence" is a commonly used phrase used to justify all manner of absurdity (usually by politicians). The absence of evidence does not rule in or rule out anything.
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It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb" It is not absolutely clear at all. The FDR does not track the thumbswitch position as far as I know. Thus, it cannot be said with certainty that there were not additional electric trim up inputs that had no effect. Your assumption seems to be based on the accuracy of Boeings publications. I do not think that any pilot, even a very bad pilot, would not make further electric trim up corrections under the circumstances. For these reasons there remain doubts in my mind. In the case of ET302 it seems the crew reactivated electric trim in desperation... following that action it is difficult to believe that they did not do so to apply constant electric trim up via the thumb switch. It is a puzzle what actually happened, but unless you KNOW what the pilots ACTUALLY did it is mere speculation rather than being "absolutely clear".