"To investigate 16 of the most prevalent claims made by conspiracy theorists, POPULAR MECHANICS assembled a team of nine researchers and reporters who, together with PM editors, consulted more than 70 professionals in fields that form the core content of this magazine, including aviation, engineering and the military.
In the end, we were able to debunk each of these assertions with hard evidence and a healthy dose of common sense. We learned that a few theories are based on something as innocent as a reporting error on that chaotic day. Others are the byproducts of cynical imaginations that aim to inject suspicion and animosity into public debate. Only by confronting such poisonous claims with irrefutable facts can we understand what really happened on a day that is forever seared into world history.--THE EDITORS
FACT: One of the clearest, most widely seen pictures of the doomed jet's undercarriage was taken by photographer Rob Howard and published in New York magazine and elsewhere (opening page). PM sent a digital scan of the original photo to Ronald Greeley, director of the Space Photography Laboratory at Arizona State University. Greeley is an expert at analyzing images to determine the shape and features of geological formations based on shadow and light effects. After studying the high-resolution image and comparing it to photos of a Boeing 767-200ER's undercarriage, Greeley dismissed the notion that the Howard photo reveals a "pod." In fact, the photo reveals only the Boeing's right fairing, a pronounced bulge that contains the landing gear. He concludes that sunlight glinting off the fairing gave it an exaggerated look. "Such a glint causes a blossoming (enlargement) on film," he writes in an e-mail to PM, "which tends to be amplified in digital versions of images--the pixels are saturated and tend to 'spill over' to adjacent pixels." When asked about pods attached to civilian aircraft, Fred E. Culick, professor of aeronautics at the California Institute of Technology, gave a blunter response: "That's bull. They're really stretching
FACT: Birnbach, who was a freelance videographer with FOX News at the time, tells PM that he was more than 2 miles southeast of the WTC, in Brooklyn, when he briefly saw a plane fly over. He says that, in fact, he did not see the plane strike the South Tower; he says he only heard the explosion.
THE WORLD TRADE CENTER
The collapse of both World Trade Center towers--and the smaller WTC 7 a few hours later--initially surprised even some experts. But subsequent studies have shown that the WTC's structural integrity was destroyed by intense fire as well as the severe damage inflicted by the planes. That explanation hasn't swayed conspiracy theorists, who contend that all three buildings were wired with explosives in advance and razed in a series of controlled demolitions.
Widespread Damage
CLAIM: The first hijacked plane crashed through the 94th to the 98th floors of the World Trade Center's 110-story North Tower; the second jet slammed into the 78th to the 84th floors of the 110-story South Tower. The impact and ensuing fires disrupted elevator service in both buildings. Plus, the lobbies of both buildings were visibly damaged before the towers collapsed. "There is NO WAY the impact of the jet caused such widespread damage 80 stories below," claims a posting on the San Diego Independent Media Center Web site (sandiego.indymedia.org). "It is OBVIOUS and irrefutable that OTHER EXPLOSIVES (... such as concussion bombs) HAD ALREADY BEEN DETONATED in the lower levels of tower one at the same time as the plane crash."
FACT: Following up on a May 2002 preliminary report by the Federal Emergency Management Agency (FEMA), a major study will be released in spring 2005 by the National Institute of Standards and Technology (NIST), a branch of the U.S. Department of Commerce. NIST shared its initial findings with PM and made its lead researcher available to our team of reporters.
The NIST investigation revealed that plane debris sliced through the utility shafts at the North Tower's core, creating a conduit for burning jet fuel--and fiery destruction throughout the building. "It's very hard to document where the fuel went," says Forman Williams, a NIST adviser and a combustion expert, "but if it's atomized and combustible and gets to an ignition source, it'll go off."
Burning fuel traveling down the elevator shafts would have disrupted the elevator systems and caused extensive damage to the lobbies. NIST heard first-person testimony that "some elevators slammed right down" to the ground floor. "The doors cracked open on the lobby floor and flames came out and people died," says James Quintiere, an engineering professor at the University of Maryland and a NIST adviser. A similar observation was made in the French documentary "9/11," by Jules and Gedeon Naudet. As Jules Naudet entered the North Tower lobby, minutes after the first aircraft struck, he saw victims on fire, a scene he found too horrific to film.
"Melted" Steel
CLAIM: "We have been lied to," announces the Web site AttackOnAmerica.net. "The first lie was that the load of fuel from the aircraft was the cause of structural failure. No kerosene fire can burn hot enough to melt steel." The posting is entitled "Proof Of Controlled Demolition At The WTC."
FACT: Jet fuel burns at 800° to 1500°F, not hot enough to melt steel (2750°F). However, experts agree that for the towers to collapse, their steel frames didn't need to melt, they just had to lose some of their structural strength--and that required exposure to much less heat. "I have never seen melted steel in a building fire," says retired New York deputy fire chief Vincent Dunn, author of The Collapse Of Burning Buildings: A Guide To Fireground Safety. "But I've seen a lot of twisted, warped, bent and sagging steel. What happens is that the steel tries to expand at both ends, but when it can no longer expand, it sags and the surrounding concrete cracks."
"Steel loses about 50 percent of its strength at 1100°F," notes senior engineer Farid Alfawak-hiri of the American Institute of Steel Construction. "And at 1800° it is probably at less than 10 percent." NIST also believes that a great deal of the spray-on fireproofing insulation was likely knocked off the steel beams that were in the path of the crashing jets, leaving the metal more vulnerable to the heat.
But jet fuel wasn't the only thing burning, notes Forman Williams, a professor of engineering at the University of California, San Diego, and one of seven structural engineers and fire experts that PM consulted. He says that while the jet fuel was the catalyst for the WTC fires, the resulting inferno was intensified by the combustible material inside the buildings, including rugs, curtains, furniture and paper. NIST reports that pockets of fire hit 1832°F.
"The jet fuel was the ignition source," Williams tells PM. "It burned for maybe 10 minutes, and [the towers] were still standing in 10 minutes. It was the rest of the stuff burning afterward that was responsible for the heat transfer that eventually brought them down.
Puffs Of Dust
FACT: Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest intact floor. Unable to absorb the massive energy, that floor would fail, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process "pancaking," and it does not require an explosion to begin, according to David Biggs, a structural engineer at Ryan-Biggs Associates and a member of the American Society of Civil Engineers (ASCE) team that worked on the FEMA report.
WTC 7 Collapse
CLAIM: Seven hours after the two towers fell, the 47-story WTC 7 collapsed. According to 911review.org: "The video clearly shows that it was not a collapse subsequent to a fire, but rather a controlled demolition: amongst the Internet investigators, the jury is in on this one."
FACT: Many conspiracy theorists point to FEMA's preliminary report, which said there was relatively light damage to WTC 7 prior to its collapse. With the benefit of more time and resources, NIST researchers now support the working hypothesis that WTC 7 was far more compromised by falling debris than the FEMA report indicated. "The most important thing we found was that there was, in fact, physical damage to the south face of building 7," NIST's Sunder tells PM. "On about a third of the face to the center and to the bottom--approximately 10 stories--about 25 percent of the depth of the building was scooped out." NIST also discovered previously undocumented damage to WTC 7's upper stories and its southwest corner.
NIST investigators believe a combination of intense fire and severe structural damage contributed to the collapse, though assigning the exact proportion requires more research. But NIST's analysis suggests the fall of WTC 7 was an example of "progressive collapse," a process in which the failure of parts of a structure ultimately creates strains that cause the entire building to come down. Videos of the fall of WTC 7 show cracks, or "kinks," in the building's facade just before the two penthouses disappeared into the structure, one after the other. The entire building fell in on itself, with the slumping east side of the structure pulling down the west side in a diagonal collapse.
According to NIST, there was one primary reason for the building's failure: In an unusual design, the columns near the visible kinks were carrying exceptionally large loads, roughly 2000 sq. ft. of floor area for each floor. "What our preliminary analysis has shown is that if you take out just one column on one of the lower floors," Sunder notes, "it could cause a vertical progression of collapse so that the entire section comes down."
There are two other possible contributing factors still under investigation: First, trusses on the fifth and seventh floors were designed to transfer loads from one set of columns to another. With columns on the south face apparently damaged, high stresses would likely have been communicated to columns on the building's other faces, thereby exceeding their load-bearing capacities.
Second, a fifth-floor fire burned for up to 7 hours. "There was no firefighting in WTC 7," Sunder says. Investigators believe the fire was fed by tanks of diesel fuel that many tenants used to run emergency generators. Most tanks throughout the building were fairly small, but a generator on the fifth floor was connected to a large tank in the basement via a pressurized line. Says Sunder: "Our current working hypothesis is that this pressurized line was supplying fuel [to the fire] for a long period of time."
WTC 7 might have withstood the physical damage it received, or the fire that burned for hours, but those combined factors--along with the building's unusual construction--were enough to set off the chain-reaction collapse.
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"PM consulted more than 300 experts and organizations in its investigation into 9/11 conspiracy theories."
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