Re checklist for trim runaway. The top line states the condition as ‘uncommanded’ trim movement. But in the MAX, at any time that MCAS is active, then the trim can move, being perceived ‘as uncommanded’; what then should a crew do ?
Even with detailed knowledge of the system, trim movement in a high workload situation demanding close attention at low speed, manoeuvring, or increasing thrust environment, the crew may not have sufficient mental capacity to recall the nuances of a complex sub system to judge normal or abnormal MCAS operation.
Associated system alerts can aid recognition of a failed state, but such assessment requires effortful thought in a time critical situation. The task has added complexity of opposing cues such as stick shaker requiring nose down pitch, airspeed comparison do nothing, or trimmed condition increasingly nose-down requiring urgent nose-up intervention.
Add to that the possibility of different annunciations or pilot interpretations across flight deck - what then CRM !
A complex, tight-coupled, intractable system, often cited as central themes in hazardous conditions.