Computer-Related Incidents with Commercial Aircraft

A Space Shuttle Control Incident


Synopsis After a delay in a space shuttle mission in 1981, the crew put in some time in the simulator in Houston. They tested a "Transatlantic abort" sequence, which dumps fuel and leads to a landing in Spain. The flight control computers "locked up and went catatonic". It turns out that an exception condition was generated by a `computed GOTO' (in the avionics software written in HAL/S), which led to an operating system livelock (the FCOS was written in assembler). The incident was recounted by Tony Macina and Jack Clemons to Alfred Spector and David Gifford for the Case Study: The Space Shuttle Primary Computer System, in Communications of the ACM 27(9), September 1984, pp874-900. The relevant excerpt is reprinted here.

Should we consider the Shuttle to be a transport category airplane? (Civilians have travelled on it.) Whatever, the incident is instructive, as well as interesting history.