PAXboy seems to have a point. the tail could very well have left the a/c before the explosion/fire. someone on the ground mightn't notice a silver panel disappearing into a blue or grey sky, but they'd sure as hell notice the flash of an explosion or the bang that it makes.
Anyway, if you were at rockaway with the a/c climbing out, would you even be able to see the tail normally?
Further to that, we all saw the fin, and it was cleanly broken off and it wasn't scorched.
I reckon we can take the witnesses at their word, its just that they probably only noticed the a/c when the chain of events leading to the crash were well underway.
regards,
BGPM.