And I contend

That there were virtually NO spreading fires. The smoke we saw from the tower tops, almost IMMEDIATELY emanated from all floors above the impact zone. That says to me -coupled with smoke curling out of the sealed window units- that fires were SET simultaneously on all the floors above the impact zone. What were these set fires? Thermite or thermate ... in the supporting structure of columns and especially in the massive hat trusses. There were probably thermitic fires occurring in the external wall columns too.

They had to take the hat trusses apart before they could collapse the building because the hat trusses held the buildings together from the top. Had the hat trusses NOT been cut apart first, they would have lain on top of the rubble intact and OBVIOUSLY indicated to even a casual observer ... that they weren't cut off by a plane strike.

-Vince