WTC 1: The NIST grossly over-exaggerates tilt during initial failure

All descriptions of early movement of WTC1 within NCSTAR 1-6D are quoted below. The descriptions of early movement of WTC2 are also listed so as to compare how the NIST understands the early movement of each tower in relation to the other.

It will become clear from the quotes that the NISt considered WTC1 to lean and move in a very similar way to WTC2, tilting about the same amount as the columns fail throughout the building before the upper portion begins to fall vertically.



WTC1: "First exterior sign of collapse was at floor 98. Rotation of at least 8 degrees to the south occurred before the building section began to fall vertically under gravity." -xliv

Comparison with the description of WTC2: "Tilt of approximately 3 to 4 degrees to the south and 7 to 8 degrees to the east occurred before building section fell." - page xliv


According to the NIST, WTC1 rotated as much to the south before falling vertically as WTC2 tilted to the east.
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WTC1: "The section of the building above the impact zone tilted to the south (observed at about 8 degrees) as column instability progressed rapidly from the south wall along the adjacent east and west walls (see figure E-11), resulting in increased gravity load on the core columns." - page liv

(fig E-11 is the same as fig 5-8 shown below)

Comparison to description of WTC2: "The section of the building above the impact zone tilted to the east and south (observed at about 7 to 8 degrees to the east and about 3 or 4 degrees to the south, Fig. E-16) as column instability progressed from the east wall to the adjacent south and north walls." -page lviii
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WTC1: "First exterior sign of collapse was at floor 98. Rotation of at least 8 degrees to the south occurred before the building section began to fall vertically under gravity." - p 312


" The section of the building above the impact zone began tilting to the south (observed at 8 degrees, table 5-2) as column instability progressed rapidly from the south wall along the adjacent east and west walls (see fig 5-8) resulting in increased gravity load on the core columns. The change in potential energy due to downward movement of building mass above the buckled columns exceeded the strain energy that could have been absorbed by the structure. Global collapse ensued.” - p 314

Figure 5-8 is shown below.



Comparison with the description of WTC2:

"tilt of approximately 3 to 4 degrees to the south and 7 to 8 degrees to the east occurred before building section fell." - page 319

"The section of the building above the impact zone tilted to the east and south (observed at about 3 to 4 degrees to the east and about 7 to 8 degrees to the south, Fig. 5-16) as column instability progressed from the east wall to the adjacent north and south walls. The change in potential energy due to downward movement of building mass above the buckled columns exceeded the strain energy that could have been absorbed by the structure. Global collapse ensued." -page 321
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All references to the early movement of WTC1 during collapse initiation from NIST NCSTAR 1-6 are listed below.

There are 2 ways to clarify what the NIST is actually describing in these quotes. One could look at the collective WTC1 quotes alone or one could compare each quote with the corresponding quote on WTC2. Both the WTC1 quotes and the the corresponding quotes of WTC2 movement are provided to remove any doubt about their intended meaning.



WTC1: "The WTC 1 building section above the impact and fire area tilted to the south as the structural collapse initiated, as shown in Fig. E-6. A tilt to the south of at least 8 degrees occurred before dust clouds obscured the view and the building section began to fall downward." -page liv

comparison to the WTC2 description:

"The building section above the impact and fire area tilted to the east and south as the structural collapse initiated as shown in fig. E-8. There was approximately a 3 to 4 degree tilt to the south and a 7 to 8 degree tilt to the east prior to significant downward movement of the upper section". - page liv
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WTC1: "The entire section of the building above the impact zone began tilting as a rigid block (all four faces, not only the bowed and buckled south face0 to the south (at least about 8 degrees) as column instability progressed rapidly from the south wall along the adjacent east and west walls." - page lxviii

comparison to the WTC2 description:

"The entire section of the building above the impact zone began tilting as a rigid block (all four faces, not only the bowed and buckled east face) to the east (about 7 to 8 degrees) and south (about 3 to 4 degrees) as column instability progressed rapidly from the east wall along the adjacent north and south walls. The building section abofve the impact continued to rotate to the east as it began to fall downward and rotated to at least 20 to 25 degrees." -page lxix
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WTC1: "A tilt to the south of at least 8 degrees occurred before dust clouds obscured the view and the building section began to fall downwards." - page lxxv

Comparison to the WTC2 description:

"Estimates made from photographs indicate that there was approximately a 3 degree to 4 degree tilt to the south and a 7 degree to 8 degree tilt to the east, prior to significant downward movement of the upper portion of the building" -lxxvi
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WTC1: "A tilt to the south of at least 8 degrees occurred before dust clouds obscured the view and the building section began to fall downwards." - page 155

"Rotation of the building section above the impact and fire zone to at least 8 degrees to the south occurred before the building section began to fall vertically." -page 156


Comparison to the WTC2 description:

"Estimates from photographs indicated that there was approximately a 3 to 4 degree tilt to the south and a 7 to 8 degree tilt to the east prior to significant downward movement of the upper building section." - page 167

This particular engineer must have been smoking a non-tobacco product before writing this:

"Rotation of approximately 4 to 5 degrees to the south and 20 to 25 degrees to the east occurred before the building section begins to fall vertically." - page 169
(He was better off using the copy-paste function like the other guys.)
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WTC1: "Rotation of at least 8 degrees to the south occurred before the building section began to fall vertically under gravity." -page 298

"The entire section of the building above the impact zone began tilting as a rigid block (all four faces, not only the bowed and buckled south face) to the south (at least 8 degrees) as column instability progressed rapidly from the south wall along the adjacent east and west walls" -page 300

"The section of the building above the impact zone began tilting to the south at least about 8 degrees as column instability progressed rapidly from the south wall along adjacent east and west walls, as shown in Fig. 9-13." - page 304

Comparison to the WTC2 description:

Same dude smoking the non-tobacco product

"Rotation of approximately 4 to 5 degrees to the south and 20 to 25 degrees to the east occurred before the building section began to fall vertically." - page 306

"The entire section of the building above the impact zone began tilting as a rigid block (all four faces; not only the bowed and buckled east face) to the east (about 7 to 8 degrees) and south (about 3 to 4 degrees) as column instability progressed rapidly from the east wall along the adjacent north and south walls." - page 308 and again on page 309

Misrepresenting the WTC1 original column failure sequence from the north, northwest, northeast and west

As anyone should be able to verify from the comparison of the NIST WTC1 and WTC2 tilt descriptions in NCSTAR 1-6 and 1-6D, the NIST represents the tilt over which all columns originally fail as about 7 degrees to the east for WTC2 and about 8 degrees to the south for WTC1.

But careful observation and measurements show that for WTC1 all columns, core and perimeter, had failed within a 1 degree tilt of any vertical component of the building.

The following sequences of images from NIST NCSTAR 1-6 show the visual evidence the NIST presents to support the claim that the building tilted 8 degrees as column failures propagated from south to north.
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The columns fail from south to north and from east to west so the clearly visible NW corner would be the last columns to fail.


This can be determined more precisely by using the high resolution Sauret video and tracking the movement of the northwest corner:



The velocity curve in black allows us to determine when the NW corner fails with remarkable precision. Both visual inspection and object tracking allow anyone to spot the moments of failure of the NW corner.


In the following sequence all columns had failed before the second and third photographs were taken even though the NIST misrepresents the failures as occurring during the sequence shown:

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Likewise, all columns had failed by the time the 2 photos below were taken:

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Once again, all columns had clearly failed by the time the second and third photographs were taken:

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Once again, all columns had completely failed by the time the second photo was taken:

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In the next case all columns had completely failed before all 3 photographs were taken:


As anyone can see who reads the NIST descriptions of the collapse initiation movement for WTC1 and WTC2 in NCSTAR 1-6D, the NIST sees the WTC1 tilt to the south just as it sees the WTC2 tilt to the east: about 8 degrees before the hinge columns gave way. There is no doubt that both tilts are described as having the same magnitude before the hinge columns gave way.




The NIST description of WTC1 southward tilt quoted was illustrated by 2 independent researchers:

R Mackey illustrates the NIST description of WTC1 building movement:


In the following interview at 11:35 and 14:50: http://www.youtube.com/watch?v=kDvDND9zNUk


R Mackey at 11:35 and 14:50: "We are talking 8 degrees of tilt. That is what the NIST reports. They report 7 or 8 degrees rotation about 1 axis and 2 to 3 degrees about another."

R Mackey: "At 8 degrees rotation, this is the point at which the hinge is completely broken and the upper block will start to fall straight down....this is what we see on the video".


Likewise, Greg Urich gives the following illustration of the NIST description:





The NIST description of WTC1 early movement and observables flatly contradict the visual record of the event.



Comparing key points of the NIST description to observables and measurables: Checking the NIST claims for accuracy

A few measurable and observable phenomena during the collapse initiation sequence:


Upper West Wall Pulls Inward 9.5s before Collapse

Antenna Base Shifts Eastward 9.5s before Collapse

This movement from 9.5 seconds before the visual collapse are the earliest sign of collapse initiation, not the 98th floor failure 9.5 seconds later as the NIST claims.


Earliest Ejections from fl 95, W Face, S Side

The NIST claims the first signs of collapse initiation were from ejections along the 98th floor. The first visible ejections were from the 95th floor.



Concave Roof Deformity Measured by Drop Curves

The NIST claims that the south wall failed first and redistributed the load to the core and adjacent east and west walls. But points traced on the antenna and the NE, NW and near the SW corner reveal concave deformity along the roofline, not convex deformity or the whole upper portion tilting as a "rigid block" as the NIST claims.


Minimal Tilt: Less than 1 Degree before Falling

The NIST clearly states at least an 8 degree tilt caused by the failure of the south wall as columns failed from south to north. But all core and perimeter col;umns had failed before any vertical component tilted 1 degree. Their entire collapse initiation scenario is based on this false assumption; that both WTC1 and WTC2 tilted about the same magnitude during the initial column failure sequence.

Drift and Drop Movements Traced and Plotted: Summary


Both N and W Perimeter Walls Fail Within 0.5s Interval

This observable and measurable fact should have alerted the NIST that their description of the initial tilt angle was wildly incorrect.


88th Fl S Face Light Grey Ejection

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The collapse initiation sequence seems to begin with a set of 11 distinct smoke pulses rising from the roofline

Direct link to video: http://www.youtube.com/watch?feature=player_detailpage&v=xGAofwkAOlo

These pressure variations can be seen in momentary concentrated smoke puffs aimed upwards at the following times on the clip

SW corner (to the right): :07, :16, :21, :27

SE corner (to the left): :30

I'm counting 11 in total, 5 from the SE corner.at least 6 distinct accelerated pulses from the SW corner


The aspect I've found most strange is how, when watching the clip, I know at what moment the collapse begins by the rapid, concentrated smoke release upwards from the SE corner just before the building starts to move (at 0:31)



These puffs...

1) are so large they are easy to notice
2) accelerate upwards faster than the surrounding smoke movement
3) are always near or at the corners of the roof

Please notice that the last of these pulses, from the SE corner, is perfectly timed with collapse initiation. Intiation begins just as the pulse shoots upward.
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Within the video there is a shaking of the camera 9.5 seconds before visible collapse. A couple of posters have identified visible creep of both the antenna and NW corner beginning at the moment of the shake. The shake in the camera provides a great reference point with which we can watch the initiation sequence.

We now know that the following motion begins at the moment of the shake:

Upper West Wall Pulls Inward 9.5s before Collapse

Antenna Base Shifts Eastward 9.5s before Collapse

With this knowledge, please look carefully at the timing of the 11 distinct roofline smoke pulses again. Notice that a distinct set of pulses rise just as the camera shakes. (I am not implying the shake means any physical thing, but it is a great reference point to see when measurable, active creep begins. It gives the timing of the pulses a connection to the whole recorded and measured process.)