Ariane 5, Flight 501: The Exception That Destroyed a Rocket
On June 4th, 1996, Europe launched Ariane 5 for the first time. About forty seconds after the flight sequence began, the rocket veered off course, broke up and destroyed itself. The engines were fine. The weather was fine. What failed was a data conversion in code that had no reason to be running. This story gets retold a lot, usually as "an integer overflow blew up a rocket". The inquiry board's report (chaired by Jacques-Louis Lions, published July 19th, 1996) tells a more useful story. The c…