As you said if it looks, waaddles, quacks and lays eggs like a duck, it probably is a duck.
If a plane with that much fuel on board smacks into and through a building that building (if not built in the last 6 years) will more than likely fall straight to the ground once the trusses weaken due to the intense heat of the inferno (Carpets, wood, insulation, chemicals, and everything else that burns in a building - apart from the plane of course).
So pick a building and try it.
Not so hard when you think about it - just look at the duck (eg) the plane and watch it quack (eg) fly into the building and then watch it waddle (eg) set of a chain of fatal events that weaken the basic structures of the building.
