Was it coincidence that all these flights were empty?
The loads were all extremely light - 45, 67 etc, highest count on one flight was 94. For a 767 or even a 757, these are light loads. This would have made it much easier to control the pax and get them to the back of the plane. Would have been much harder if there'd been 230 on board. Did the attackers have access to res systems to target these flights?