"Even at this point, prior to finalising the specific camera and additional building positioning, an error in the NIST value of at least 7.5 degrees has been identified.
If a camera placement is determined within a 100ft error of margin, the NIST angle is out by over 7 degrees.
If a camera placement is determined within a 10ft error of margin, the NIST angle is out by over 9 degrees."
The NIST clearly relies upon this angle for subsequent damage analysis and their explanation for the cause of collapse as shown by their own approach outlined in NCSTAR 1-6.
Please notice that the entire tree of damage analysis roots from the box "aircraft impact damage analysis". All other stages in analysis are dependent upon it.
A second independent study has been done on the incoming aircraft trajectory here:
The second study agrees with the first.
The NIST Inward Bowing Collapse Initiation Model
WTC1 experienced the same inward bowing along a face with long span trusses. Yet collective core failure occurred in WTC1. It was described as south wall failure within the NIST report, but the claim was based on a type of cartoon caricature scenario in which WTC1 is misrepresented as tilting about the same magnitude as WTC2.
The observable reality is that a pronounced inward bowing of the south wall was followed by a collective core failure from south to north over a tilt of less than 1 degree. This points directly to inward bowing as being a visible sign of impending collective core failure.
Also. in the case of WTC7 careful study of the collective core failure and the perimeter responding direcctly through a flexure belding shows that the building fell through the core.
Could the same be true in the case of WTC2; that it was also initially pulled down through partial core failure? Perhaps the inward bowing witnessed along the east face was due to partial core failure instead of the sagging floor trusses as the NIST claims. The NIST collapse initiation mechanism for both WTC1 and 2 is based on sagging long span floor trusses which pull in the perimeter.
If the NIST report on WTC1 wasn't guided on the incorrect claim that the building tilted significantly to the south as columns failed, they would have been testing models based on collective core failure for WTC1. They would have been aware that the substantial inward bowing seen on the south face was followed by collective core failure over minimal tilt less than 10 minutes later.
If the NIST described early movement of WTC1 correctly, perhaps there would never have been an attempt to associate south wall IB with floor sagging. South wall IB would have been interpreted as a sign of impending core failure instead.
In the case of WTC2, IB is less pronounced and is located just above a row of MER panels.
The relation between the spandrels being pulled inward and the MER panels and associated welds must have a sizable connection with the amount of IB witnessed.
Is the inward bowing the result of sagging floor trusses as the NIST claims, or a system of partial core failure as certainly seemed to be the actual case of WTC1?
The north wall is on the right and the east wall is on the left. The NIST did not include the pull-in of the north wall as seen in the image above in their report. The simultaneous pull-in of both the north and east walls in this way clearly suggests that the corner column of the core is moving downward in order to cause this effect.
Interestingly, the same effect was witnessed in the case of WTC1 during the earliest visible movement along the west wall. The west perimeter adjacent to the cornermost core column (CC1001) was pulled inward during the earliest visible movements of the building, as clearly demonstrated in this linked video.
COMPARISON OF NIST DESCRIPTION OF EARLY MOVEMENT WITH THE ACTUAL VISUAL RECORD
All NIST descriptions of the collapse initiation process of WTC2 were already produced along with to the corresponding quote for WTC1 in section 2.3.
In section 3.2 the collective visual record of the WTC2 collapse is examined directly and independently. The movement of the structure during the initial column failure sequence is mapped and traced back to the earliest point of detectable movement from multiple angles. It is clearly shown that features of the WTC2 initial failure sequence can be understood as a rapid succession of 8 identifiable events occurring in the following order:
Action above the 75th floor:
1) Deformations: Inward bowing of the east face
2) Earliest detectable movement: 81, 82nd fl spandrels pull in sharply (along east and north walls)......................
3) Earliest ejections, 78th fl ejections: .....................
4) East wall separates into upper and lower parts, East wall upper portion is pulled inward and behind the lower portion
5) Tilting begins
Flash and destruction of NE corner, floor 90
Failure sequence of the north and south perimeter walls over tilt of __ degrees
Action along the 75th floor:
6) 75th fl east face row of ejections
7) 75th fl west wall north and south quarter of MER panels ejected from building with flooring still attached. NW and SW MER corners are destroyed, west wall upper portion falls out and over lower portion. 8) Dropping of the upper portion
There is no need to speculate about these events since they are directly observable and captured in video and photographs, and therefore verifiable.
It is interesting to ask how many of these distinct observable features were spotted and noted in the NIST report on the WTC2 collapse.
The NIST did not seem to notice how the north wall was pulled along with the east wall during the earliest movements of the visible collapse initiation sequence.
They also did not notice how all columns of WTC1 failed within 1 degree of tilt. They also did not notice how the west wall of WTC1 was pulled in just as the north wall of WTC2 was pulled in during early movement.
Without noticing any of these features, the NIST claims that both WTC1 and WTC2 initially failed due to sagging long span floor trusses that pulled in the south and east sides, respectively, and initiated a tilting process of an ~8 degree magnitude in both buildings.
What other visible features of the WTC2 collapse initiation process did the NIST overlook?
Action above the 75th floor:
1) Deformations: Inward bowing of the east face
2) Earliest detectable movement: 81, 82nd fl spandrels pull in sharply (along east and north walls)
The NIST noticed the east face pull-in but did not seem to notice how it happened together with panels along the north face.
The same feature was overlooked in the case of WTC1
3) Earliest ejections, 78th fl ejections:
The NIST did not seem to notice how the earliest rows of ejections emerged along 2 distinctly different lines separated by about 3 floors. The first row of ejections emerged as a symmetrical pattern of 7 ejections. This pattern seems to have not been observed by the NIST.
4) East wall separates into upper and lower parts, East wall upper portion is pulled inward and behind the lower portion
The NIST describes the mechanism accounting for this as the sagging of long span floor trusses.
5) Tilting begins
N
Flash and destruction of NE corner, floor 90
This was not commented upon in the NIST report
No distinct collapse behavior along the 75th floor is mentioned within the NIST report.
Action along the 75th floor:
6) 75th fl east face row of ejections
7) 75th fl west wall north and south quarter of MER panels ejected from building with flooring still attached. NW and SW MER corners are destroyed, west wall upper portion falls out and over lower portion. 8) Dropping of the upper portion
None of these phenomena are mentioned within the NIST reports.
