It doesn't sound to me like they where particularly fatigued, although the preflight banter is certainly eye opening. It sounds like they got high on the approach and where unstable, descending in vertical speed mode because they never captured the profile. They never briefed and where seemingly unaware of the high terrain just underneath the glidepath, apparently saw the runway at DA, disconnected and went visual but never arrested the excessively high vertical speed or where already too low at that point.

Sad in many ways. The transcript reads like a textbook, professional crew doing it like they had a check airman in the jumpseat. Everything done professionally right up to the point where they continued an unstable approach into the ground.

The only warnings the EGPWS provided where "sink rate". They got a "too low, terrain" apparently after they where already hitting trees. I wonder if the autopilot disconnect warning covered up a EGPWS warning that could have saved them.