they were standby pilots in the cockpit jumpseats with false IDs. they just walked away when the planes landed after the order was given to ground them.
Oh yeah, now I remember those pilots. I'm starting to forget facts from 9/11 after these few years. Well some of the second wave may have been pax.
Another thing I've forgotten...did Mohammed Atta and the others use their real names when they bought tickets? If so, and the others never thought about the possibility of grouding the planes, they probably would have used their real names too, the better to be listed in glory on TV.