Point WTC7-3: The Claim in NIST’s Final Report that WTC 7 Came Down in Free Fall Without Explosives

The Official Account

In its Final Report on WTC 7, [1] issued in November 2008, NIST finally acknowledged that WTC 7 had entered into free fall for more than two seconds. NIST continued to say, however, that WTC 7 was brought down by fire, with no aid from explosives.

The Best Evidence

Scientific analysis [2] shows that a free-fall collapse of a steel-framed building could not be produced by fire, that is, without explosives (a fact that NIST’s lead investigator, Shyam Sunder acknowledged [3] in his discussions of NIST’s Draft Report for Public Comment in August 2008).

References for Point WTC7-3

This analysis has been confirmed by NIST itself, in “Questions and Answers about the NIST WTC 7 Investigation,” NIST, August 2008 (originally at www.nist.gov/public_affairs/factsheet/wtc_qa_082108.html). This version of the document, which was posted at NIST’s website at the time its Draft version of its WTC 7 report was published, has been replaced by a version

in which NIST continues to acknowledge a 2.25-second stage of “gravitational acceleration (free fall).”

[3] Sunder said: “A free fall time would be [the fall time of] an object that has no structural components below it. … The … time that it took … for those 17 floors to disappear [was roughly 40 percent longer than free fall]. And that is not at all unusual, because there was structural resistance that was provided in this particular case. And you had a sequence of structural failures that had to take place. Everything was not instantaneous” (“WTC 7 Technical Briefing,” NIST, August 26, 2008). Although NIST originally had a video and a transcript of this briefing at its Internet website, it removed both of them. However, the video is now available

Also available is its transcript, under the title