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The Pentagon Attack

At around 9:39 AM, after both towers had been hit but before either had exploded, a 757 thought to be Flight 77 approached the Pentagon. Having flown over the capital from the north, it ultimately approached the west block of the Pentagon from the southwest, after making a 270-degree turn while descending 7000 feet.

The jetliner was less than 100 feet overhead as it swooped over stalled traffic on the highway adjacent to the large lawn and heliport on the west side of the sprawling building. Some eyewitnesses said that the plane banked left and its left wing hit the heliport. Witnesses variously describe the plane crashing into the facade, hitting the ground in front of the facade it and exploding, disappearing into the building, and being swallowed by rings of smoke. They agree that there was a huge explosion and fireball, and torrents of smoke in the wake of the strike. Some describe small fragments of aircraft raining down.

Some onlookers were surprised at the lack of apparent aircraft debris in front of the Pentagon, and some remarked that the impact hole seemed small given the size of the jetliner. Similar observations based on photographs of the crash zone shortly after the attack have fueled controversy over the attack, and theories that something other than a 757 hit the Pentagon that day.

A section of the building above the heavily damaged first and second floors collapsed about 20 minutes after the initial attack.

No Impact Photos

In the minutes following the attack, the FBI confiscated from nearby businesses video recordings that might have captured the attack. In contrast to the well-documented tower crashes and collapses in Manhattan, the story of Flight 77 crashing into the Pentagon had no corroborating pictures, only eyewitness accounts and photos of the building's damaged facade. And those post-collapse photos convinced many researchers that no Boeing 757 crashed into the building. In early 2002, the Pentagon released a series of five images from a security camera, supposedly showing the moments of impact. However, the images show evidence of manipulation.

s u m m a r y
title: The Five-Sided Fantasy Island
authors: Richard Stanley and Jerry Russell
This highly original article breaks with the orthodoxy in the skeptics' community about the Pentagon attack, by suggesting that the popular drone and/or missile attack theories were cultivated by the perpetrators to create a "false dialectic". Stanley and Russell suggest that the damage to the building was accomplished with internal demolitions rather than an aerial assault, and provide support for Eastman's theory that Flight 77 overflew the Pentagon.

Faint Seismic Signal

Both of the tower impacts were recorded by seismic observatories, and so was the crash of Flight 93. In contrast, scientists had difficulty finding the seismic signal for the Pentagon crash.

e x c e r p t
title: Seismic Observations during September 11, 2001, Terrorist Attack
authors: Won-Young Kim and Gerald R. Baum
Since the time of plane impact at the Pentagon had often been reported with large scatter, the United States Army contacted us to inquire whether we could obtain an accurate time of the Pentagon attack on September 11, 2001 based upon our seismic network. We analyzed seismic records from five stations in the northeastern United States, ranging from 63 to 350 km from the Pentagon. Despite detailed analysis of the data, we could not find a clear seismic signal. Even the closest station (Delta = 62.8 km) at Soldier's Delight, Baltimore County, Maryland (SDMD) did not record the impact. We concluded that the plane impact to the Pentagon generated relatively weak seismic signals. However, we positively identified seismic signals associated with United Airlines Flight 93 that crashed near Shanksville, Somerset County, Pennsylvania. The time of the plane crash was 10:06:05 +/- 5 (EDT).

A page once on the geo.arizona.edu website contained a brief report with a seismogram showing a clear signal labeled "Arrival of the seismic energy from the collision [of Flight 77]". (See seismogram image in right margin.) Curiously, later versions of this report contained a retraction and referred to Dr. Kim's report:

... preliminary analysis indicated that the impact might have produced a seismic signal that was recorded at the USGS station CBN, but later work showed this not to be the case. The best work on the forensic seismology of the impact is by Dr. Kim ... 1  

Some researchers have seized on Kim's report as evidence that no 757 crashed at the Pentagon. However this is not the conclusion of the scientists who wrote the report, and such an inference is not justified for a number of reasons.

  • The interpretation of seismic data is a complex subject, depending on details of geology between the event and the station, among other things. The fact that obvious signals were generated by 767s ramming into steel towers in Manhattan anchored to granite bedrock should not lead us to expect that a 757 crashing into a heavy masonry wall of a sprawling building on an alluvial plain of the Potomac River.
  • The seismic stations whose data was analyzed in the report were all at least 35 miles from the Pentagon, much further than the stations that recorded events at the World Trade Center were from Lower Manhattan.
  • Of the various types of seismic disturbances that are recorded by seismic recording stations, plane crashes apparently generate only strong S-waves -- vibrations in which the displacement is perpendicular to the ground. The strength of an S-wave produced by a plane crash would presumably be highly dependent on the inclination of the plane's trajectory from the horizontal plane of the ground. Since by all accounts, the Pentagon attack plane approached at a very shallow inclination, perhaps at an angle of less than 10 degrees, we would expect any S-waves generated by the impact to be very weak.


1. Forensic seismology analysis of the terrorist attacks on the pentagon, geo.Arizona.edu, [cached]

page last modified: 2010-12-18
Copyright 2004 - 2011,911Review.com / revision 1.08 site last modified: 12/21/2012
Photographs taken immediately after the crash don't show obvious signs of debris from an airliner crash.
Photographs of the cleanup of the Pentagon crash found on DOD websites show no evidence of jetliner parts.
Scraps alleged to be from the crashed aircraft are notable for their small size.
This seismic signal was recorded by the USGS CBN seismic station located about 50 miles from the Pentagon.