Overview: An examination of the July 17, 1996, tragedy involving the Paris-bound TWA Flight 800, which exploded 12 minutes after taking off from New York's JFK International Airport. Included: animation that shows how a fuel-tank explosion caused the plane to break apart; a look at initial concerns that terrorism may have been to blame, and how the National Transportation Safety Board determined the probable cause---an electrical short circuit. David Mattingly reports.