Originally Posted by
yoko1
While I don't disagree in theory, this approach has two distinct problems.
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Second, let's just say that the switchology was changed back to the NG configuration and we inserted this new step into the existing Runaway Stab Trim procedure. For the sake of discussion we will call it Step 6 since Step 5 is where the cutout switches are used. In order to get to Step 6, the pilots must correctly navigate Steps 1 thru 5. Since neither accident crew chose to utilize the existing Runaway Stab procedure, much less work through it step by step (and particularly that very critical Step 2), then a new switch with a new step really would not have solved their problem.
As I mentioned above, new tools don't help much if they are not used or used ineffectively. The accident crews had several tools available to them that they either did not use or did not use effectively. I think a bit more time and energy should be directed to figuring out why that was the case before we go down the path of creating new tools.
Agreed that a big question is why (both) crews did not effectively control trim when they should/could have since manual electric trim inputs did stop MCAS for 5 seconds, as documented and confirmed by fdr traces
I do disagree though that had step6 (re-enable manual electric trim only) been available it would not have helped ET:
Once they realized that manual mechanical trim was not available, due lack of training on use of flip out handles and/or aero loads alone, step 6 would have allowed them to re-trim the aircraft, even though they had not followed the memory items perfectly.
BTW: I totally understand the frustration with those who focus on trim motor overload, in ET case manual electric trim was clearly working until the cutout switches were activated.
Although the 'blips" at the end of each accident trace are puzzling in the Lion air case they coincide with transfer to co-pilot, in ET they are in extreme conditions which could well have had a biomechanical affect on the pilots ability to manipulate the switches.