Ariane 5 Flight 501
loreprogramming
The 1996 maiden launch destroyed by an integer overflow in software reused from Ariane 4.
Thirty-seven seconds after liftoff on June 4, 1996, a 64-bit velocity value overflowed a 16-bit conversion inside inertial-alignment code inherited from Ariane 4, where the flight profile made the overflow impossible; on the faster Ariane 5 it was not. The exception took down both redundant units running identical code, the rocket veered and self-destructed, and roughly half a billion dollars of vehicle and payload fell into the Atlantic. The Lions report made it the eternal case study on reusing code outside its validated envelope.