Context of 'February 27, 1993: WTC Engineer Says Building Would Survive Jumbo Jet Hitting It'

In the wake of the WTC bombing, the Seattle Times interviews John Skilling who was one of the two structural engineers responsible for designing the Trade Center. Skilling recounts his people having carried out an analysis which found the Twin Towers could withstand the impact of a Boeing 707. He says, “Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed.” But, he says, “The building structure would still be there.” [Seattle Times, 2/27/1993] The analysis Skilling is referring to is likely one done in early 1964, during the design phase of the towers. A three-page white paper, dated February 3, 1964, described its findings: “The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact.” However, besides this paper, no documents are known detailing how this analysis was made. [Glanz and Lipton, 2004, pp. 131-132; Lew, Bukowski, and Carino, 10/2005, pp. 70-71] The other structural engineer who designed the towers, Leslie Robertson, carried out a second study later in 1964, of how the towers would handle the impact of a 707 (see Between September 3, 2001 and September 7, 2001). However, the National Institute of Standards and Technology (NIST), following its three-year investigation into the WTC collapses, will in 2005 state that it has been “unable to locate any evidence to indicate consideration of the extent of impact-induced structural damage or the size of a fire that could be created by thousands of gallons of jet fuel.” [National Institute of Standards and Technology, 9/2005, pp. 13]

Pat Patterson. [Source: Publicity photo]Los Angeles FBI agent Pat Patterson is sent to Yemen to assist in the investigation of the USS Cole bombing (see October 14-Late November, 2000). While there, he spends several evenings with John O’Neill, the special agent in charge of the FBI’s national security division in New York, who is leading the investigation. O’Neill is the FBI’s top expert on al-Qaeda and Osama bin Laden. The two men speculate about what bin Laden’s next target might be, and end up considering the World Trade Center. Patterson will later recall: “I thought it was unlikely they would hit a target a second time, but John was convinced of it. He said, ‘No, they definitely want to bring that building down.’ He just had that sense and was insistent about it.” [New York Magazine, 12/17/2001; Weiss, 2003, pp. 291-292 and 321] After leaving the FBI, O’Neill will actually start work as director of security for the World Trade Center shortly before 9/11 (see August 23, 2001).

Leslie Robertson. [Source: Publicity photo]Leslie Robertson, one of the two original structural engineers for the World Trade Center, is asked at a conference in Frankfurt, Germany what he had done to protect the Twin Towers from terrorist attacks. He replies, “I designed it for a 707 to smash into it,” though does not elaborate further. [Chicago Tribune, 9/12/2001; Knight Ridder, 9/12/2001] The Twin Towers were in fact the first structures outside the military and nuclear industries designed to resist the impact of a jet airplane. [Robertson, 3/2002; Federal Emergency Management Agency, 5/1/2002, pp. 1-17] The Boeing 707 was the largest in use when the towers were designed. Robertson conducted a study in late 1964, to calculate the effect of a 707 weighing 263,000 pounds and traveling at 180 mph crashing into one of the towers. He concluded that the tower would remain standing. However, no official report of his study has ever surfaced publicly. [Glanz and Lipton, 2004, pp. 138-139, 366] A previous analysis, carried out early in 1964, calculated that the towers would handle the impact of a 707 traveling at 600 mph without collapsing (see February 27, 1993). In 2002, though, Robertson will write, “To the best of our knowledge, little was known about the effects of a fire from such an aircraft, and no designs were prepared for that circumstance.” [Robertson, 3/2002] The planes that hit the WTC on 9/11 are 767s, which are almost 20 percent heavier than 707s. [Scientific American, 10/9/2001; New Yorker, 11/19/2001]

Dr. Abolhassan Astaneh-Asl examines steel from the World Trade Center. [Source: University of California, Berkeley]An engineer investigating the remains of the World Trade Center sees melted girders and other evidence that the towers experienced extreme temperatures on 9/11. Dr. Abolhassan Astaneh-Asl is a professor of civil and environmental engineering at the University of California, Berkeley. He specializes in studying structural damage done by earthquakes and terrorist bombings. [Chronicle of Higher Education, 12/7/2001; CBS News, 3/11/2002] He arrives in New York on September 19 to conduct a two-week scientific reconnaissance of the collapsed towers, hoping to gain an understanding of how they had come down. His project is one of eight financed by the National Science Foundation to study the WTC disaster. [New York Times, 10/2/2001; Berkeleyan, 10/3/2001; US Congress. House. Committee on Science, 3/6/2002] He examines numerous pieces of steel taken from Ground Zero. [Chronicle of Higher Education, 12/7/2001] Astaneh-Asl will describe the WTC as “the best-designed building I have ever seen.” [San Francisco Chronicle, 10/22/2001] Yet he notices unusual warping and other damage in its remaining steel:
At a recycling center in New Jersey, he sees 10-ton steel beams from the towers that look “like giant sticks of twisted licorice.” [Chronicle of Higher Education, 12/7/2001] He shows the San Francisco Chronicle a “banana-shaped, rust-colored piece of steel” that has “twisted like toffee during the terrorist attack.” [San Francisco Chronicle, 10/22/2001]
He later recalls, “I saw melting of girders in [the] World Trade Center.” [PBS, 5/10/2007]
He notes that steel has bent at several connection points that had joined the floors of the WTC to the vertical columns. He describes the connections as being smoothly warped, saying, “If you remember the Salvador Dali paintings with the clocks that are kind of melted—it’s kind of like that.” He adds, “That could only happen if you get steel yellow hot or white hot—perhaps around 2,000 degrees.” [Chronicle of Higher Education, 12/7/2001]
Astaneh-Asl says that steel flanges have been reduced “from an inch thick to paper thin.” [Berkeleyan, 10/3/2001]
He finds a foot-long twisted shard of steel that is “like a piece of bread, but it was high-strength steel.” He comments, “I haven’t seen anything like this [before].” [Berkeley Daily Planet, 10/20/2001]
He finds “severely scorched [steel] members from 40 or so floors below the points of impact [by the planes].” He believes this is the result of the planes having destroyed the elevator walls, thereby allowing burning jet fuel to pour down into the building, igniting fires hundreds of feet below the impact floors. [CBS News, 3/12/2002]
He says that, in some places, the fireproofing used to protect the WTC steel has “melted into a glassy residue.” [New York Times, 10/2/2001]
Astaneh-Asl sees a charred I-beam from WTC Building 7, which collapsed late in the afternoon of 9/11. “The beam, so named because its cross-section looks like a capital I, had clearly endured searing temperatures. Parts of the flat top of the I, once five-eighths of an inch thick, had vaporized.” [New York Times, 10/2/2001]
Other individuals will report seeing molten metal in the remains of the World Trade Center in the weeks and months after 9/11 (see September 12, 2001-February 2002), and data collected by NASA reveals dozens of “hot spots” (some over 1,300 degrees Fahrenheit) at Ground Zero (see September 16-23, 2001). But Thomas Eagar—an engineering professor at the Massachusetts Institute of Technology—later comments that the “temperature of the fire at the WTC [on 9/11] was not unusual, and it was most definitely not capable of melting steel.” [Eagar and Musso, 12/2001] Yet Astaneh-Asl will later put forward the “tentative” conclusion, “The collapse of the [Twin Towers] was most likely due to the intense fire initiated by the jet fuel of the planes and continued due to burning of the building contents.” [Astaneh-Asl, 11/30/2003 ] Astaneh-Asl is a member of the team assembled by the American Society of Civil Engineers to investigate the World Trade Center site after 9/11 (see September 12, 2001), though he will resign from this because he disagrees with its decision to keep findings secret until the initial inquiry has been completed. [New York Times, 10/2/2001; Associated Press, 9/6/2002]

Recovery efforts end at the World Trade Center site. [Associated Press, 5/31/2002]