This might be common knowledge, but I had no idea:
On the morning of the September 11, 2001 attacks, MacFarlane was scheduled to return to Los Angeles on American Airlines Flight 11 after being a keynote speaker at his alma mater in Rhode Island. In 2005, on episodes of Loveline and Too Late with Adam Carolla, MacFarlane stated that he tried to make the flight, but arrived about ten minutes after final boarding ended. At 8:14 a.m., fifteen minutes after the departure of American Airlines Flight 11, the plane was hijacked, later being flown into the North Tower of the World Trade Center in New York City. He was told he would need to wait for the next flight and then sat down next to someone as they were watching the attacks and he said to the man beside him, “I was supposed to be on that flight."-- Seth MacFarlane [Wikipedia]
For those who didn't know, MacFarlane is creator (and many of the voices) of Family Guy and American Dad. At one point he stated he wouldn't use 9/11 in his humor due to the experience but has since (thankfully) reversed that.