Impact of 9/11 attacks on air travel

The 2001 attacks on New York’s World Trade Center has had marked effects on air travel.

Everyone remembers the event, of course: On Sept 11, 2001, al-Qaeda militants hijacked four US passenger planes and plowed two of them into the World Trade Center in New York, one into the Pentagon in Virginia and the fourth into a field in Pennsylvania. Apart from the (still-ongoing) political fallout, this was a momentous event in aviation history, as it was the first suicide attack by terrorists using civilian aircraft.