... 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. Indeed, at that time, no fireproofing systems were available to control the effects of such fires. ... The damage created by the impact of the aircraft was followed by raging fires, which were enormously enhanced by the fuel aboard the aircraft. The temperatures above the impact zones must have been unimaginable; ... Figure 3 shows the comparative energy of impact for the Mitchell bomber that hit the Empire State Building during World War II, a 707, and a 767. The energy contained in the fuel is shown in Figure 4. Considerations of larger aircraft are shown in Figures 5 and 6. The physical sizes of these aircraft are compared with the size of the floor plate of one of the towers in Figure 7. These charts demonstrate conclusively that we should not and cannot design buildings and structures to resist the impact of these aircraft. ... To the extent that the structural design of the World Trade Center contributed to the loss of life, the responsibility must surely rest with me. At the same time, the fact that the structures stood long enough for tens of thousands to escape is a tribute to the many talented men and women who spent endless hours toiling over the design and construction of the project . . . making us very proud of our profession. ...