I was flying westbound TATL in mid-air when 9/11 happened; was very lucky and landed at YYZ instead of the dozens of planes that diverted to Gander. Knew something was up on final approach as the airport was shut down and the tarmac full of planes parked every which way, but had no idea of what until an hour after landing. Took 4 days before was able to cross the border to re-enter the US (and it took many hours of waiting at security). Quite a time. Hope it never happens again.