NCSTAR 1A Draft (Aug 08)
3.6 Collapse Time
Describes the process used to measure the time it took 18 floors to drop out of view.
They observed 5.4 s with an u'ncertainty of no more than 0.1 s.'
p40-41
NIST then stated that this time was approx. 40% longer than the computed free fall time..
Chandler wanted to have them include instantaneous acceleration, so in their final report they did (nov 08). It showed that the overall time was 40% longer than 'computed freefall time' (same as before, and same as I measured in my video way back when) but gave the instantaneous acceleration for various intervals along the way.
Out of that period of 5.4 s, roughly 2.25 s was approximately at freefall acceleration. This means that it was slower than freefall for about 58% of that portion.
The relevant question is, what specifically makes this brief period of freefall so important? After all, neither of the towers collapsed at freefall acceleration, so truthers don't dwell on that fact when examining them.
It seems rather arbitrary to suddenly seize on this aspect of WTC 7's collapse as particularly important. It cannot be explained by controlled demolition, which couldn't produce this kind of effect in the first place, and certainly not without loud explosions, which were not evident.
So keep flogging this dead horse already, it doesn't help the truther cause, except with the ignorant.