I think it's entirely possible that extremist sympathisers who are ex-military or airline pilots from Iraq, Iran, Afghanistan or Pakistan (and maybe others) were involved. Having an ATPL doesn't make one necessarily right-minded, nor does being an extremist (of whatever persuasion) make it impossible for one to have the skill to fly an airliner. There are, I'm sure, 757/767 sims (or sims of similar types of aircraft)in those countries, and it may be very difficult to establish whether any unusual use was made of them recently.
Velvet:
I find it very unlikely that the crashes (for they must have crashed, having been shot down) of four further large aircraft would have gone un-noticed in the current media bunfest. Nothing of that nature could possibly have been suppressed; Americans would have been on to the phone to the local TV companies immediately anything fell out of the sky, and we would probably have home-video footage of some of it. No, I think that one is wishful thinking on the part of some local radio or TV junior hack.
[ 12 September 2001: Message edited by: Scroggs ]