Ariane 5, Flight 501: How One Overflow Blew Up a Rocket in 40 Seconds
On 4 June 1996, the first Ariane 5 self-destructed 37 seconds after launch. The cause: an overflow converting a 64-bit float to a 16-bit int in reused Ariane 4 code. A first-person breakdown: what happened, why redundancy didn't help, and six QA lessons on code reuse, boundaries, dead functionality, error handling, and testing in the real configuration.