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In 2000 users on airliner's message board discussed what would happen if an airliner crashed into the World Trade Center.
You can still view the discussion here.
IIRC the FBI did investigate and determined no foul play, nor were any of the terrorist involved in this post in any way. Just a coincidence.
There was also reports that the FBI had anticipated the possibility of terrorist using explosive-laden jets to attack the towers but they assumed they'd use smaller private jets like gulf-streams and would use 4 or so to hit the towers. After 1993 lots of people knew the towers were a target. Lots of people that fled the towers on 9/11 had worked there during the 1993 bombing and instinctively knew something was off and they needed to get out of them ASAP.