Staggeringly long day - I do not think that would be a legal assignment in the US. Fatigue could very easily have played a leading role in this unfortunate debacle. My brain certainly gets fried quite easily on a long duty day.
Oilhead - In the UK we're currently governed by time of day and number of sectors flown. On the assumption the crew checked in around 0700L the allowable Flying Duty in 12.15hrs.
Not sure if the F word is appropriate, maybe sleepiness. If we're looking at the F word we need to look at other area's,maybe commuting. The Airline the crews work for have a scheduling agreement which along with the regulations offer some protection against fatigue. The other area mentioned before was stress.