The Lone Gunmen pilot.

This might be old news to you. The first episode of the X-Files spinoff The Lone Gunmen, from March 2001, concerned a plot to fly a plane into the World Trade Center.

Supposedly, this kind of plan was around for a while, even in a Tom Clancy novel. So I guess it's not an original invention of the writers here. Of course, there's an anti-government spin in the storyline which is particularly tasty. No, I don't think the terrorists "got the idea" from this episode.

Watching it now is chilling. (So is the horrendous acting.)