I listened to an interview of a flight attendant who laid it all out - planes were boarded but taken to hangars where the passengers were forced to make calls, being told they were part of the war games happening that day. She suspects the planes that actually hit the building were not the same passenger planes, and those people were locked inside the aircraft on land, and gassed to death after completing the calls about "hijackers". It was pretty convincing. There were probably 6-8 aircraft involved.