1.   A fourth jetliner also was hijacked and crashed into a field outside Pittsburgh.

2.   By the time accounts of the fourth jetliner reached the public, the resistance to the terrible truth was gone.

3.   It also dispatched members of its Aviation Incident Response Team to New York, Washington, and suburban Pittsburgh, where a fourth jetliner crashed.

4.   A fourth jetliner crashed in a Pennsylvania field, presumably after some passengers overpowered the hijackers.

5.   A fourth jetliner, also apparently hijacked, crashed in Pennsylvania as the part of the closely timed series of attacks.

6.   A fourth jetliner, also apparently hijacked, crashed in Pennsylvania.

7.   A fourth jetliner, flying from Barcelona to New York, was in the air and awaiting clearance into a Canadian airport, an airline official said.