PENTAGON RESEARCH

BUILDING PERFORMANCE REPORT

This is a very important topic to understand. This is the only official report produced in regards to the aircraft and the building at the Pentagon. Almost all of the information relayed by other agencies including the 9/11 Commission is from this report. Remember the NTSB was not allowed to do an aircraft accident report and the FBI has published nothing and refuses to release video. The rest of this page will be text from the actual report. It is to demonstrate how the report was created and its assumptions. In the sidebar a few critical flaws will be detailed. A link to the full report is at the bottom of this page.

"The volume of information concerning the aircraft crash into the Pentagon on September 11 is rather limited. Through the cooperation of transportation, law enforcement, and news organizations the BPS team was able to collect the essential data for the purpose of this study." (page 12)

"Members of the BPS [Building Performance Study] team inspected the site on two occasions. Between September 14 and September 21, 2001, team leader Paul Mlakar had limited access [See sidebar] to the site while rescue and recovery operations were still in progress. On this early inspection visit, he examined the exterior of the building and portions of the building interior.

"Controlled access to the site was granted to the full team after rescue and recovery operations were complete. On October 4, 2001, the Pentagon team, together with John Durrant, the executive director of ASCE’s institutes, and W. Gene Corley, the BPS team leader at the World Trade Center, inspected the interior and exterior of the damaged area of the Pentagon for approximately four hours.

"The inspection of the BPS team focused on obvious physical damage, primarily in the region of the impact. This inspection was not comprehensive. It did not address fire damage to concrete as a material, and it did not result in full documentation of all physical damage or as-built construction.

"By the time the full Pentagon BPS team visited the site, all debris from the aircraft and structural collapse had been removed and shoring was in place wherever there was severe structural damage. The design team charged with reconstructing the Pentagon was assessing the building and preparations were being made to demolish the areas for reconstruction. Consequently, the Pentagon BPS team never had direct access to the structural debris as it existed immediately after the aircraft impact and subsequent fire.

The teams attempted to inspect and photograph all columns with significant visible damage and most of the beams and floor bays with significant visible damage. To the extent possible, it was noted whether physical loads or the effects of fire caused the observed damage. The BPS team also noted the performance of windows and exterior wall reinforcements that had been installed to enhance blast resistance in Wedge 1 prior to the attack. However the BPS team inspections were not comprehensive, and they did not address fire-related material degradation." (page 24)

"At a depth of approximately 160 ft into the building, columns 3G, 3H, 3J, and 5J were damaged but still standing, although in the direct path of the fuselage. With a maximum spacing of less than 14 ft between pairs of these columns in a projection perpendicular to the path of the fuselage, it is highly unlikely that any significant portion of the fuselage could have retained structural integrity at this point in its travel. More likely, the fuselage was destroyed much earlier in its movement through the building. Therefore, the aircraft frame most certainly was destroyed before it had traveled a distance that approximately equaled the length of the aircraft.

"The debris that traveled the farthest traveled approximately twice the length of the aircraft after entering the building. To come to rest at a point 310 ft from the area of impact at a speed of 780 ft/s [530 MPH - See sidebar], that debris experienced an average deceleration of approximately 30g.

"The influence of the structure on the deceleration of the aircraft (and,conversely, the influence of the aircraft on the structure) can be appreciated by comparisons with examples of aircraft belly-landed in controlled circumstances. In 1984, the Federal Aviation Administration (FAA) conducted a controlled impact demonstration (Department of Transportation 1987) to evaluate the burn potential of antimisting kerosene fuel. In that test, the FAA landed a Boeing 720 aircraft (weighing approximately 175,000 lb) without landing gear on a gravel runway at Edwards Air Force Base. The aircraft in that test was flying at approximately 250 ft/s when it made first contact, but it slid approximately 1,200 ft before it stopped. Although the test aircraft was traveling at approximately one-third the speed of the aircraft that struck the Pentagon, its sliding distance was approximately 3.9 times that of the Pentagon attack aircraft. Clearly, the short stopping distance for the aircraft striking the Pentagon derived from the energy dissipated through the destruction of the aircraft and building components; the acceleration of building contents; the loss of lift when the wings were severed from the aircraft; and effective frictional and impact forces on the first-floor slab [See sidebar], the underside of the second-floor slab, and interior columns and walls.

"A study of the locations of fatalities also yields insight into the breakup of the aircraft and, therefore, its influence on the structure. The remains of most of the passengers on the aircraft were found near the end of the travel of the aircraft debris. The front landing gear (a relatively solid and heavy object) and the flight data recorder (which had been located near the rear of the aircraft) were also found nearly 300 ft into the structure [See sidebar]. By contrast, the remains of a few individuals (the hijacking suspects), who most likely were near the front of the aircraft, were found relatively close to the aircraft’s point of impact with the building. These data suggest that the front of the aircraft disintegrated essentially upon impact but, in the process, opened up a hole allowing the trailing portions of the fuselage to pass into the building.

"Several columns exhibited severe bends. However, the predominant evidence suggests that these columns generally did not receive impact from a single, rigid object. Instead, the deformed shapes of these columns are more consistent with loads that were distributed over the height of the columns.

"The analyses of the available data reveal that the wings severed exterior columns but were not strong enough to cut through the second-floor slab upon impact. The right wing did not enter the building [See sidebar] at the point where it struck the second-floor slab in its plane. The damage pattern throughout the building and the locations of fatalities and aircraft components, together with the deformation of columns, suggest that the entire aircraft disintegrated rapidly as it moved through the forest of columns on the first floor. As the moving debris from the aircraft pushed the contents and demolished exterior wall of the building forward, the debris from the aircraft and building most likely resembled a rapidly moving avalanche through the first floor of the building.

Fire damage generally was similar to that normally resulting from serious fires in office buildings. Clearly, some of the fuel on the aircraft at impact did not enter the building, either because it was in those portions of the wings that were severed by the impact with the facade or with objects just outside of the building [See sidebar], or because it was deflected away from the building upon impact with the facade; that fuel burned outside the building in the initial fireball. Generally, fire damage to columns, beams, and slabs was limited to cracking and spalling in the vicinity of the aircraft debris. There were two areas with more severe damage. One area, to the north of the path of the aircraft, was bounded approximately by column lines 4, 7, A, and D. The other area, to the south of the path of the aircraft, was in the vicinity of column lines K and L and crossing column lines 11, 12, and 13. In both areas, there was more serious spalling and cracking than occurred typically throughout the fire area. Fire damage on the second floor in the vicinity of the path of the aircraft was generally more severe than in the same areas directly below on the first floor." (pages 40-42)