Bigmouth - good query, but possibly misleading.
Aside from damage caused by fire, there doesn't seem to be so very much impact damage to the P building. It is visually quite consistent with the 200,000-400,000 ft pounds that a Rockwell single could deliver on square blow, vs the 200 - 400 million ft pounds from a heavy aircraft at roughly 100x the weight and 10x the velocity.
Reports state that the pilot used to fuel at Linate in Transit to get a break on Swiss fuel taxes, so quite possibly he was traveling light on fuel. Another hundred gallons would have made some difference in intensity of the fire, but not soooo much as thousands and thousands of gallons.
The big difference is that the Pirelli Building is a 'curtain wall' structure in which central reinforced concrete castings support the works, along with columns distributed about the floors. The outer covering is intentionally as 'light' as possible to minimize loading, In the 50's, when the P building was constructed, the engineers had more 'respect' for gravity, so they were generous in application of structural materials. You could remove ALL of the exterior glass walls and the building would still stand nicely....until rain ate the rebar.
By contrast, the WTC buildings really depended for their rigidity and structural integrity on the unique exterior wall of stainless steel girders and crossbrace structures now familiar to many as rubble. That design is/was inherently much more vulnerable to fatal damage from a massive external impact that cuts the structure. It was no coincidence that Governor Rockefeller & clan were in the STEEL business and not the concrete business. From a hundred years hindsight, history may be more inclined to treat the WTC's as a political boondoggle gone terribly wrong -- but that concept is not very PC at the moment.
Last edited by arcniz; 20th Apr 2002 at 18:34.