from 911Research Website
Video Evidence of the North Tower's Destruction
These frames were extracted from the footage of the North Tower collapse in the documentary, WTC: The First 24 Hours. Each of the twelve frames in this sequence is separated by 1/2 second. We created the sequence in order to study the descent of the radio tower relative to the visible facade. The radio tower's descent is first apparent in frame 6, but the facade's descent is not visible until frame 8. The radio tower descends about 10 feet relative to the facade.