meleagertoo, #4589
‘how can it be possible for two professional pilots on a type with a known and highly public failure mode to appear not to be aware of it's symptoms when it occurs to them?’
You appear blinded by hindsight.
The first symptoms and alerts immediately after takeoff were of low speed, approach to stall, erroneous air-data. The crew managed this situation correctly, concluding UAS.
Note that the alerts and annunciations for UAS are similar, identical to the emergency AD re MCAS except there was no trim activity.
Subsequently, flap retraction, MCAS moved the trim. Previous discussions have considered the salience of trim activity and time required to conclude a failure in an intermittent system.
The combination of increased stick force - ‘fly the aircraft’, and UAS could be interpreted as control difficulties - speed error could affect the feel of the aircraft - as would trim.
Thus the crew required a step change in their mindset to associate the revised situation with MCAS, or at least trim problems and then isolate the trim system.
Surprise, startle; the original problem understood, now its not !