Items19The creator’s order
  1. 1Mariner 1Mariner 1NASA's first attempt at Venus was destroyed by the range safety officer about five minutes after launch on 22 July 1962. Newspapers blamed a missing hyphen; most later accounts describe a missing overbar in the handwritten guidance equations, so the software used unsmoothed velocity data and…0
  2. 2Therac-25Therac-25A radiation therapy machine involved in at least six massive overdoses between 1985 and 1987; three of the patients later died. It dropped the hardware interlocks of earlier models and relied on software reused from them, where those interlocks had masked the same defects. One fault was a race…0
  3. 3AT&T long-distance network collapse of 1990AT&T long-distance network collapse of 1990For about nine hours on 15 January 1990, much of AT&T's long-distance network refused calls. A software update installed in December had a misplaced "break" in C code, which jumped out of a "switch" statement early in the routine that handled recovery messages. When one switch reset and announced…0
  4. 4Patriot missile failure at Dhahran (1991)Patriot missile failure at Dhahran (1991)On 25 February 1991 a Patriot battery at Dhahran failed to engage an Iraqi Scud, which hit a barracks and killed 28 soldiers of the US Army's 14th Quartermaster Detachment. The system counted time in tenths of a second, and truncation in a 24-bit fixed-point register meant the error grew the longer…0
  5. 5Ariane flight V88Ariane flight V88The first Ariane 5 broke up 37 seconds after launch on 4 June 1996, taking the four Cluster science spacecraft with it. Inertial reference code reused from Ariane 4 converted a 64-bit floating-point value, the horizontal bias, into a 16-bit signed integer. Ariane 5's faster trajectory produced a…0
  6. 6Mars PathfinderMars PathfinderA success story with a scare in the middle. Days after landing on Mars on 4 July 1997, Pathfinder's computer began resetting itself: four resets, on 5, 10, 11 and 14 July. The cause was priority inversion in its VxWorks software, where a low-priority task held a shared resource that a high-priority…0
  7. 7Mars Climate OrbiterMars Climate OrbiterThe units mix-up everyone has heard of, and the part most people miss. Lockheed Martin's ground software reported thruster impulse in pound-force seconds, while NASA's navigation software expected newton-seconds, a factor of 4.45. Small errors added up over the cruise, and on 23 September 1999 the…0
  8. 8British Post Office scandalBritish Post Office scandalThe most human entry here. Fujitsu's Horizon accounting system, rolled out across Post Office branches from 1999, showed shortfalls that subpostmasters could not explain, and more than 900 of them were prosecuted between 1999 and 2015 on the strength of its figures. In Bates v Post Office in 2019…0
  9. 9Year 2000 problemYear 2000 problemThe failure that mostly did not happen, which is exactly why it belongs here. Decades of software stored years as two digits to save memory, so 2000 would read as 1900 and break date arithmetic. Worldwide remediation cost an estimated $308 billion, and the problems that did appear on 1 January 2000…0
  10. 10Northeast blackout of 2003Northeast blackout of 2003Power lines sagging into overgrown trees in Ohio started it, but software turned a local problem into a blackout affecting an estimated 55 million people across the north-eastern United States and Ontario on 14 August 2003. A race condition in the alarm system of FirstEnergy's GE XA/21 energy…0