Reply #9: Robertson about the aircraft impacts and the design... [View All]

[Carefulplease]

Reflections on the World Trade Center

Leslie E. Robertson

The lead structural engineer reflects on the rise and fall of the World Trade Center towers.

http://www.nae.edu/nae/bridgecom.nsf/weblinks/CGOZ-58NLCB?OpenDocument

The buildings survived the impact of the Boeing 767 aircraft, an impact very much greater than had been contemplated in our design (a slow-flying Boeing 707 lost in the fog and seeking a landing field). Therefore, the robustness of the towers was exemplary. At the same time, the fires raging in the inner reaches of the buildings undermined their strength. In time, the unimaginable happened . . . wounded by the impact of the aircraft and bleeding from the fires, both of the towers of the World Trade Center collapsed.

The jets impacting the WTC1 and WTC2 probably had 6 and 10 times more kinetic energy, respectively, than the impact that was contemplated in their design.