FACT:-
25 September 1978; Pacific Southwest 727-200; San Diego, CA: The aircraft had a midair collision with a single engine Cessna and crashed. All seven crew members, all 128 passengers, both occupants of the second aircraft, and 13 others on the ground were killed.
OK, so if it can happen by accident then it can happen deliberately...
I was trying to think of a plan of action to avoid rather than have to defend if its possible or not...