1945 B-25 bomber crash

Fact

The B-25 bomber crash inflicted relatively light damage to the building.

The size of a B-25 bomber is much smaller than a Boeing 767, with smaller wingspan and smaller fuel capacity. A B-25 bomber has a wingspan of 67 feet, compared with 156 feet for a Boeing 767. The fuel capacity of the B-25 bomber was 1,000 gallons, as compared with 24,000 gallons for a Boeing 767. As well, the speed at which a B-25 bomber travelled was far less than the ~500 mph than the speed that the two Boeing 767's were travelling when they hit the World Trade Center.

The World Trade Center was designed to withstand the force from the impact of a Boeing 707, lost in the fog and travelling at a relatively slow speed of 180 miles per hour.

The Boeing 767 aircraft that hit the World Trade Center were significantly heavier, with fuel for transcontinental flights. American Airlines Flight 11 was travelling at 470 miles per hour when it crashed into the North Tower at 8:46 a.m. United Airlines Flight 175 was travelling at 590 miles per hour when it crashed into the South Tower.

The energy contained in an airplane or other moving object is proportional to the velocity.

where m is the object's mass (in kg) and v is the object's speed (in m·s⁻¹).

Aircraft	Boeing 767 - North Tower	Boeing 767 - South Tower	Boeing 707
Calculation	(179,168 kg * 210.12)/2	(179,168 kg * 263.72)/2	(163,293 kg * 80.46722)/2
Energy	3,954,417,824	6,229,464,421	528,658,660

The engineers also did not consider how fires resulting from a crash would affect the buildings. It was a combination of the damage from the impact of the Boeing 767's, and the resulting fires that ultimately caused the steel columns to weaken to the point where they failed and the building collapsed.

Matthys Levy, an architect at Weidlinger Associates and the author of "Why Buildings Fall Down" (Norton, 1992), watched the first tower collapse while standing at Seventh Avenue and Houston Street, some 20 blocks away. "I saw the beginning of the top moving down, and the whole thing collapsed in a cloud of smoke," Mr. Levy said. "From what I saw, it seemed to come straight down." Mr. Levy said the situation was much different from the one that occurred in 1945 when a much smaller plane slammed into the Empire State Building. That plane, a bomber with a smaller impact and less fuel, ripped a 20-foot hole in the structure, but the building remained standing.^[1]

But Anthony G. Cracchiolo, director of priority capital programs for the Port Authority of New York and New Jersey, which owned the buildings, said little thought had been given to the possibility of a plane crash into the towers. "We never were asked to consider trying to protect the building from such a threat," said Mr. Cracchiolo, who was among those who coordinated the reconstruction after the 1993 bombing. "As structural engineers, there is nothing we could have done to protect the building from a direct impact from a plane as large as these."^[1] Melvin Schweitzer, a member of the Port Authority board of commissioners from 1993 to 1999, said, however, that the board repeatedly inquired about that possibility. "We were just told that architects had explained that the building was designed to withstand a jet," Mr. Schweitzer said. "Frankly, when we raised that question, most of us were thinking of a small plane."^[1]

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