By Rick Rajter – October 26, 2006

One of the major oddities of all WTC2 videos is the apparent lack of plane deceleration from many of the observed camera angles. The plane seems to fly in effortlessly, but then comes to a complete stop while inside (apparently violating conservation of momentum and energy). To the layman, these two conservation laws mean we should expect TWO major sources of slowdown when one object penetrates another:
• Energy is lost via dissipation as the intruding object breaks and destroys the impacted area into smaller pieces
• Energy is transferred to the broken pieces in the form of kinetic energy or gained velocity.
A quick example: If I throw a baseball through a window, the dissipation of energy occurs in breaking the big piece into little pieces and velocity gained by little pieces as they fly away from the original window location. The kinetic energy of the ball is a finite supply used up as these two processes occur. At UA flight 175’s alleged impact speeds (estimated anywhere between 500-600 mph depending upon the source), a 767 speeding at reasonably full weight would have some 4 billion joules of KE for consideration.
Considering that KE energy is a finite source to draw from, a key question arises: “Do the videos show deceleration, or are zero deceleration claims hogwash?” To the best of our knowledge, Stefan Grossman (presumably helped by Marcus Icke) did the first numbered, reproducible frame-by-frame analysis of the flight 175 image. Using the Fairbanks video, Grossman calculates a zero percent deceleration. In fact, as the plane enters the building, some frames appear to show a slight acceleration. This is most bizarre and must be either a 1) measurement error on Grossman’s behalf or 2) a creation error on the TV-fakery side. Reality, of course, makes acceleration impossible. I personally think it is a measurement error from a single frame, as this acceleration frame comes right after a deceleration frame. Thus, if this one data point is an error, it implies an offsetting error in an adjacent frame, given the fixed aggregate time budget.
Eric Salter followed with his own analysis and claimed 13% deceleration based on frame-by-frame study using one of the 2-3 Fairbanks video variants. One of the suspicious facts about the Fairbanks video(s) is that the FBI had possession of them before they went public.
There is a major flaw in Salter’s analysis. He used an overlay or “trace” to match the blurry 767 image to judge its speed. The problem is that it is hard to match a wide-line trace or outline of a plane against a blurry plane image with real consistency.
Salter is inconsistent in choosing an anchor point to locate his trace against the video plane image. When the image is outside the building, Salter anchors the trace at the main wings. After the plane is mostly inside the building, Salter switches and anchors the trace at the back of the tail wing. The trace never matches the image perfectly: outside the building “excess” tail wing shows to the left of the outline, but inside the building, this excess disappears. Therefore, Salter artificially slows down his plane trace yet the plane blur goes off ahead and Voila! Deceleration falsely established.

For my own analysis, I decided to use the widely known Scott Myers camera pictures, so I didn’t have to worry about compression issues, frame rates, etc. I found the highest resolution version I could get my hands on in order to minimize loss or measurement precision. The 15-picture spread was (allegedly) taken using fixed 0.033 second intervals, features a nearly fixed camera angle, and has a fairly decent contrast on key plane features. Thus, it is perfectly suited for frame-by-frame analysis, one of the best videos in terms of high signal-to-noise ratio.
Using photoshop, I took all 15 sections and placed them in one layered PSD file. I then ran a series of difference filters on each neighboring pair of frames to ensure camera positioning on the pictures had not been altered and that they were in perfect registery (by contrast in the Salter analysis, the WTC wall moves from frame to frame). A few pictures had to be moved left one pixel in order to be in closer registry to frame one. No frames were moved up, down, or right by any amount.
I used four different locations on the plane (two pre-impact positions and two post-impact positions). Of the pre-impact positions, the fuselage glare is the easiest to define, but the front of the nose also provides robust numbers and a good sanity check (reduces subjectivism). Using unaltered/un-enlarged pictures, a pixels per second average of two pre-impact locations yield a mean of 29 pixels per frame with a standard deviation of 0.6 with a sample size of 6.

The post-impact speeds were calculated in the same manner, but using two different locations on the back tail. Interestingly enough, the speeds calculated here on the best matching data points show a 29.0 pixels per frame outside the building with a standard deviation of 0.6 and sample size of 6 versus 29.6 inside the building with a standard deviation of 0.5 with a sample size of 5. In other words, I found 4% acceleration.
Can it be measurement error? It is possible, but I was analyzing under 8X magnification. But playing devil’s advocate, let’s look at a worst-case scenario. Suppose I made a 1-pixel error on EVERY measurement (perhaps I drank too much coffee and was too jittery with the mouse). That would give me an average pre-impact speed of 30 pixels/frame and a post-impact speed of 28.6 pixels/frame.
That implies a 4.6% decrease in the average velocity. Average velocity is (V_final – V_initial)/2, so that means the actual instantaneous velocity at the end of the interval would be an absolute maximum slowdown of 9%.
The endpoints of my calculations then are acceleration of 4% and deceleration of 4.6%. But the assumptions underlying the latter are severe. A more reasonable adjustment yields a middle ground estimate. The most I would be off in favor of acceleration is 0.5 pixel per interval. If so, then the maximum slowdown would be 2-2.5%.
A 2.5% loss of velocity means 95% of original KE is still avilable. If we assume 4 billion joules is a reasonable estimate of the energy pre-impact, then the plane would still have 3.8 billion joules after entering.
To double-check, I blew the frames up by 8X using adobe photoshops standard interpolation function, which gives me more precision measuring differences in pixels between the frames. This analysis, giving generous concessions to the deceleration crowd, gives a 3% instantaneous velocity slow down. In short, magnification produces no difference from the un-enlarged analysis.
In summary, if there was deceleration, it was trivial.

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