calypso:
Re ‘
What is missing in that logic is the times the machine malfunctions and it is the pilot intervention that saves the day.’ Yes; …
Reinterpreting this as the need for ‘understanding’ - knowledge of these issues and interventions, requires looking at and recording normal work, human adaptation, how often things go right.
This is widely discussed in ‘Safety II’ and ‘Resilience’; complementary ways of thinking about safety and everyday operations - view the human as an asset.
A significant point is the number of situations which might be encountered in modern aircraft (probability) and how many actually require two crew - need vs nice; and if two; what is the residual risk - time available for the resting pilot, vs a non-pilot in the other seat, getting back to the cockpit.