Vayamos por partes:

9) Se tienen en cuenta los choques de avionetas, no de aviones de pasajeros de 100 toneladas.
Preparadas para soportar el choque de un reactor comercial.

Frank A. DeMartini a manager for WTC Construction and Project Management stated in a January 2001 interview on the History Channel that "the building was designed to have a fully-loaded 707 crash into it.That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners, because this structure is like the mosquito netting on your screen door -- this intense grid. And the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting." A Boeing 707 is very comparable in size and fuel load to the planes used on 9/11. DeMartini worked on the 88th floor of the North Tower and died in the 9/11 attacks.
http://video.google.es/videoplay?doc...35121622917423