No. 009 · Cabinet of Wrong Numbers

37 Seconds of Ariane 5

· 37 seconds

  1. 1Guidance software reused from Ariane 4
  2. 2Ariane 5 flies faster; a horizontal velocity value grows larger
  3. 3Converting a 64-bit float to a 16-bit integer overflows
  4. 4Both inertial reference units fail the same way
  5. 5The rocket veers off course and self-destructs ✕

Reused code carries the assumptions of the system it was written for.

Source: Ariane 501 Inquiry Board report, July 1996

Ariane 5 Flight 501 failure, 1996. Duration: 37 seconds. 5 hops from the first change to the failure.