[supercat]

The Empire State Building survived an airplane crash on its 79th floor in 1945 because the Army Air Corps B-25 twin-engine bomber that got lost in a fog was a much smaller plane, and the building's structure was more rigid, Mr. Loizeaux said.

According to Why Buildings Fall Down, the Empire State Building was also fortunate in that the body of plane which hit it did so at floor level instead of between floors. Had it hit a few feet higher, it might have buckled one of the steel support columns and caused a major, perhaps fatal, structural failure.