I was Conference Director at a financial publishing company in NYC. As the person responsible for the dates and venues of our annual events roster, I originally organised a conference to take place at the conference suite on Floor 102 of one the Twin Towers on, you've guessed it, Tuesday, September 11, 2001.
I revised the schedule a few days later and on a completely personal *whim*, decided to change the date of that conference to Thursday, September 13th instead. I was planning to fly to London that Thursday night to be with my family for Jewish New Year which that year was on Tuesday 18th September, one week after the attacks. I only changed the conference date so that I could run the event during the day, have a drink at the Windows on the World bar afterwards and then head straight to the airport. Yes, selfishly motivated, but look at the consequences! Made me shudder when I realised.