I saw this on Seth MacFarlane’s bio on imdb.com:
On September 11, 2001 he was scheduled to return to Los Angeles on American Airlines Flight 11 after being a keynote speaker at his alma-mater in Rhode Island. Due to a mix-up by his travel agent he was told that his flight was scheduled to depart at 8:15am but it really departed at 7:45am and he had arrived at Boston Logan Airport a few minutes after boarding was stopped on his flight and he was told he would have to wait for the next flight. At 8:45am one hour after the departure of American Airlines Flight 11 it was hijacked by terrorists and crashed into One World Trade Center (North Tower) in New York City killing all on-board. He was able to contact his parents within 20 minutes of Flight 11 striking the first tower to tell them he was okay. He also said that he thanked God that his travel agent had screwed up the departure time or he would have been on board and he wouldn’t have known what to do when the terrorists took over the plane.