When American Airlines Flight 77 hit the Pentagon's exterior wall, Ring E, it created a hole approximately 75 ft. wide, according to the ASCE Pentagon Building Performance Report. The exterior facade collapsed about 20 minutes after impact, but ASCE based its measurements of the original hole on the number of first-floor support columns that were destroyed or damaged. Computer simulations confirmed the findings.
Why wasn't the hole as wide as a 757's 124-ft.-10-in. wingspan? A crashing jet doesn't punch a cartoon-like outline of itself into a reinforced concrete building, says ASCE team member Mete Sozen, a professor of structural engineering at Purdue University. In this case, one wing hit the ground; the other was sheared off by the force of the impact with the Pentagon's load-bearing columns, explains Sozen, who specializes in the behavior of concrete buildings. What was left of the plane flowed into the structure in a state closer to a liquid than a solid mass. "If you expected the entire wing to cut into the building," Sozen tells PM, "it didn't happen."
The tidy hole in Ring C was 12 ft. wide ? not 16 ft. ASCE concludes it was made by the jet's landing gear, not by the fuselage.
