Complacency
The other thing no-one has mentioned here is complacency. This pair were out on a little evening jaunt from Antigua and back, after the shuttle it would be back to the bar. The weather was lovely, only a few pax, light fuel load, a bit of VFR big jet flying in the Caribbean, it makes up for the crap days. Their guard was down and it should be a lesson to us all.
PS kotakota, you forgot he other useless thing, blue sky above you.