Two things about flight 188  

That's what they claimed, but that is just as bad or worse than being asleep. It would show a complete disregard for the safety or the aircraft and passengers. It was also claimed they were having a heated argument. It was almost certain that they were asleep, as they missed 1 hour of radio calls, and had not prepared for a descent until well overflying their destination without descending. From their altitude a descent at a standard rate would have taken 30 minutes. Fatigue was also listed as a causal factor in the Colman Q400 Flight 3407 in Buffalo.