There was a plot to do just this. And also a plot to simultaneously hijack and blow-up several airplanes.
Apologies if this has been posted already. I haven't had a chance to read thru the entire thread yet. You can place the blame for lack of follow-up on this directly at the feet of the Clinton administration:
http://www.cnn.com/2001/US/09/18/inv.hijacking.philippines/
Of course, nobody in the mainstream press is likely to repeat this anymore. They'd rather see how much traction their lie against the Bush admin gets.