Another example: The problem experienced by a BA 777 departing LHR with an unsecured fuel cap makes headline news on the BBC tonigh. It does so for the simplest of reasons, it is a mechanical failure that can be identified and someone strung up on the rack.
Fatigue is not like that. It is silent and leaves no marks in the air, although it might leave them elsewhere. I wonder if cameras in the cockpit might just help carriers to see how tired people are?