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Free Fall — Part 4 – David Chandler – Medium


by David Chandler

In Part 3 we looked at NIST’s Final Report on the Collapse of World Trade Center Building 7; Draft for Public Comment released in August 2008. We turn now to the final report released in November 2008.

During the public comment period after the release of the final draft a number of organizations and individuals, myself included, submitted “requests for correction” heavily criticizing the measurement of the descent of the building that led to the conclusion that it came down 40% slower than free fall. As we saw in Part 3, Steven Jones had wrangled a commitment to change at least the wording where the draft report said, “assuming constant velocity” to at least an acknowledgment that the building was accelerating downward. A minimal change in the wording was all any of us expected.

However, when the final report was released we were surprised to see a new analysis that acknowledged 2.25 seconds of absolute free fall! I immediately changed the title of my YouTube video that displayed my measurement of free fall to WTC7 in Freefall: No Longer Controversial. However the new NIST analysis merits more analysis.

Section 3.6 of NIST NCSTAR 1A says,

This is the original flawed analysis, which NIST still apparently defends as valid. NIST does not acknowledge any shortcomings of this approach apart from lacking detail.

Next, the report says, “A more detailed examination of the same video led to a better understanding of the vertical motion of the building in the first several seconds of descent.” The new analysis is a supplementary analysis, showing the displacement, velocity, and acceleration of the building rather than just the overall time of fall. The results are presented in a rather interesting graph:

The first thing you might notice about this graph is it is upside down relative to the graph in the header of this article. That is because the vertical axis of the graph plots the “Downward Velocity.” The orientation of the graph is not an issue.

The equation of the red regression line in Stage 2 has a slope of 32.196 ft/s² (= 9.813 m/s²), well within the margin of error of absolute free fall. NIST does acknowledge free fall. However, there is a period of gradual transition into free fall during what NIST calls Stage 1. Keep in mind that NIST is continuing to use Camera 3 (looking upward from West Street) for its measurements. They are also tracking a point near the middle of the roof line where the ambiguity between vertical and lateral motion (see Part 3) is maximum. My graph for the NW corner of the building from a level vantage point undergoes a sudden transition from support to free fall. When I use the Camera 3 video and a point near the middle of the roof line my results look almost identical to the NIST results, with the erroneous gradual transition leading into free fall. We must conclude that the gradual transition is an artifact of the deceptive camera angle. The bottom line is that the existence of a Stage 1, where the building is descending with resistance as the columns progressively buckle is a fiction.

The rounding of the graph in Stage 1 also accounts for the discrepancy between my measurement of 2.5 seconds of free fall and NIST’s measurement of 2.25 seconds of free fall. (The exact duration of free fall is not significant in terms of the implications, but I wanted to point out the source of the discrepancy in case anyone was wondering.)

Another point of clarification is the curve NIST uses to interpret the data. They give the equation of the curve, which I have plotted below.

This is the interpolation curve NIST used to describe the data. It clearly has no physical meaning. It is only a mathematical device to describe scattered data in terms of an explicit function. Beyond the range of fit to the data the curve is meaningless.

The curve has absolutely no physical significance. It is merely an interpolation curve, one that fits the data reasonably well over a certain portion of the domain. I have elsewhere described this as the mathematical equivalent of laying a wet noodle on the data and nudging it around until it fits pretty well. This procedure is not wrong. I am mentioning it in case some might think the curve is the result of some kind of high level analysis.

What is wrong with the curve is that it restates and emphasizes what is wrong with the data. There is no gradual transition to free fall. When a level camera perspective is used, eliminating the ambiguous kink in the roof line, the velocity graph takes a sharp turn. One moment the building is stationary, the next moment it is falling.

Vertical component of velocity vs time as measured from a level perspective, eliminating the deceptive ambiguity of the apparent “kink” in the roof line. Note the sharp transition from support to free fall.

The section concludes,

“As noted above, the collapse time was approximately 40 percent longer than that of free fall for the first 18 stories of descent. The detailed analysis shows that this increase in time is due primarily to Stage 1. The three stages of collapse progression described above are consistent with the results of the global collapse analyses discussed in Chapter 12 of NIST NCSTAR 1–9.” [emphasis added]

But there is no actual gradual transition. If there is no gradual transition there is no “Stage 1.” If there is no Stage 1, there is no 5.4 seconds which is being used here as the linchpin of the analysis. The 5.4 second interval and the “three stages of collapse progression” are simply fabricated.

Laced throughout this section is a repeated phrase, “the north face.”

On one level this phrase seems innocuous. The videos being used for measurements do in fact show the motion of the north face of the building. However if you dig deeper you find that the actual claim is that only the north exterior facade is falling at free fall. Page 43 shows a table of events including several seconds prior to the start of the visible collapse over which the buckling of core columns propagates from one end of the building to the other. The report claims, “The horizontal progression of buckling core columns was interior to the building and could not have been observed from the street.” Somehow NIST is imagining that the collapse of the interior of the building was decoupled from the exterior walls and occurred earlier than the collapse seen on video. In their account, only the north exterior face remained, then buckled and fell at free fall.

The supposed decoupling of the interior collapse from the visible exterior collapse, then, is NIST’s ultimate rationale for accepting free fall. This claim is both implausible and contrary to evidence that is in fact visible on videos. The WTC 7 Q&A page on the NIST web site makes the claim of decoupling even more explicit. “WTC 7’s collapse, viewed from the exterior (most videos were taken from the north), did appear to fall almost uniformly as a single unit. This occurred because the interior failures that took place did not cause the exterior framing to fail until the final stages of the building collapse. The interior floor framing and columns collapsed downward and pulled away from the exterior frame.”

How does this contradict reality? Let me count the ways! First a compilation of views from different camera angles. Compare this reality with NIST’s purported reality. Granted, we are seeing the surface of the building, but there are numerous clues to what is going on in the interior.

The fall of WTC 7 seen from numerous camera angles. Note that the building retains its stiffness and falls as a unit. Notice the lack of large deformations.

Notice that the west penthouse (on the right) is supported until about a half second prior to the visible collapse. The columns supporting it must therefore still be present up until that point.

Notice that there was window breakage below the east penthouse when it collapsed into the building several seconds earlier. There was no more window breakage, however, until the start of the visible collapse, which spawned a rash of window breakage under the west penthouse. Had there been the kind of interior disruption going on prior to the visible collapse that NIST claims, there would have been similar signs on the surface.

If the interior columns had buckled they would have pulled the floors down with them, This would have pulled inward on the exterior walls and we would see visible deformations on the surface. The girders would not pull away from the exterior walls, as the NIST Q&A piece claims, because there is no mechanism for the interior to decouple from the exterior walls. The girders strongly connect the interior columns to the exterior columns. Note that NIST’s own computer models of the collapse all involved major deformations of the exterior walls. No such large deformations were seen in the videos of the actual building, however, even as the building was falling.

Exterior deformation seen in NIST’s computer modeling.

When WTC 7 collapsed it gave rise to a huge roiling cloud of dust and debris that flowed down the street in a manner some have compared with pyroclastic flow from a volcano.

Had the interior of the building collapsed earlier, the debris cloud would have arisen ahead of the visible collapse. The large mass of the interior of the building would have broken through the exterior walls and torn apart the exterior in the process. The NIST explanation lacks even the most rudimentary plausibility.

NIST cannot just supplement the errors in the final draft report and make the errors go away. The draft report is based on the fiction of an early start time for the collapse using a manifestly unsuitable camera angle to make that determination. After being assailed by its critics (us), the final report conceded the fact of free fall while trying desperately to discount the significance of that finding. The consequences do not go away easily, however. It is clear that the building fell with a sudden transition to free fall, and that the interior of the building gave way only about a half second early, which is a common demolition technique to pull the building in on itself. The further implication is that the building had to have been demolished by an external energy source (explosives).

And so the rabbit hole opens wide. We will explore the rabbit hole in Part 5.

Something else has been learned from the NIST report, as significant as the physical analysis. As we have seen, NIST produced a report that is both implausible in general and impossible in detail. They did not do that through incompetence, because they are most assuredly not incompetent. We must conclude NIST knowingly participated in a cover-up. 9/11 was a crime, so the NIST report must be considered a criminal cover-up. 9/11 provided a false pretext for going to war, resulting in millions of deaths. Therefore NIST is participating in covering up a war crime. Questioning the official story of 9/11 has become taboo in politics, the media, in academia, and in polite society. But how is it that examining in careful detail an event that has changed the course of U.S. foreign and domestic policy and impinged on our identity as a nation can or should be considered taboo if we expect to remain a free society?

Part 5.

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