Computer-Related Incidents with Commercial Aircraft

A 1985 B747 Incident

19 February 1985

Synopsis A China Air B747, flying on autopilot high over the Pacific, suffered an engine failure, followed by loss of control, and entered an inverted spin at about 40,000 ft. After experienced +6 to -4G on the way down, it was recovered at 9,000 ft and flown carefully to SFO in a mildly damaged state. Pilot judgement was faulty in three main respects (and excellent in one - recovering quickly from the spin when it was possible!). The major misjudgement was operating the aircraft at an altitude at which an engine loss would not enable the airplane to continue flying straight-and-level above stall speed - immediate nose-down was essential for recovery. The autopilot was not designed to operate in those conditions, and gave different control inputs which caused the aircraft to enter the inverted spin. The pilots took some time to determine what was happening. The final accident report, NTSB Aircraft Accident Report NTSB/AAR-86/03 was prepared for the WWW by Hiroshi Sogame of All-Nippon Airways Safety Promotion Committee, to whom we are especially grateful. A short note recounting the accident appeared in China Air incident... the real story by Peter Trei in RISKS in October 1986, summarising an article in Flying magazine's October 1986 issue.