Just to keep the incidental information tidy, the plane that hit the Empire State Building was a B-25 Mitchell bomber, the same type that bombed Tokyo during WWII. Twin engines and small enough to take off from the deck of an aircraft carrier. The twin towers of the WTC were built to withstand being hit by a 707 (they hoped), which, I believe, was the largest airliner at the time.

Don (just bein' picky and pedantic) Firth