Willow, #394,
"In this potential situation, are the risks relating to the trim wheel [requiring two-pilot effort*] capable of being mitigated or even retired completely through specific training exercises? " * NPRM wording: - two hands or four hands ?
A guiding principle^^ is that training should not be used to mitigate a technical shortcoming; but principles come and go. (^^ a misnomer).
I doubt that there is a satisfactory answer because the situation depends on assumed probabilities, subjective interpretation of requirements, and the variability of human behaviour both in the regulatory process and ultimately operation.
In such circumstances we may be asking the wrong question.
Changing the viewpoint from the human as a hazard - to be trained, constrained, and ultimately blamed; to that of the human as a help, people who can learn in everyday operation, adapt to unforeseen situations, and thus improve safety by minimising overall risk.
The new memory checklist concentrates on using the stick-top trim switch, fly the aircraft, actions which are assumed to be instinctive. These skills can be practiced during manual flight (A/T Off), normal operations, getting the feel for the aircraft, relating trim change with speed, thrust, config change.
There could be greater safety benefit by encouraging pilots to think and learn from opportunities in normal operations - self education, experience, professionalism, airmanship, so that if a trim runaway is encountered, then the pilot will react as assumed by the checklist, instinctively and sufficiently quickly to avoid a more extreme and improbable situation. ##
Similarly the regulators and manufacturers need to change how they consider piloting contributions to safety; a help, not a hazard, a safety resource; to be used before the event, not to resolve a situation which design and regulation should prevent.
Reconsider the assumptions made about the human and operating environment, the rationales; take in the 'big picture' of aviation safety - look both ways before crossing the road - every day, normal operation.
## 'New' Emergency drill memory items Trim Runaway: -
'Firmly hold control column.
Disengage autopilot if engaged. Disengage autothrottle if engaged.
Use the control column and thrust levers to control airplane pitch attitude and airspeed.
Use main electric stabilizer trim to reduce control column forces'.
In my flying days that text described disconnecting the autos and flying manually.
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Last edited by safetypee; 7th Oct 2020 at 15:00.