BOAC Flight 712 (callsign Speedbird 712) was a British Overseas Airways Corporation (BOAC) service operated by a Boeing 707-465 from London Heathrow Airport bound for Sydney via Zurich and Singapore. On Monday 8 April 1968, it suffered an engine failure on takeoff that quickly led to a major fire; the engine detached from the aircraft in flight. After the aircraft had made a successful emergency landing, confusion over checklists and distractions from the presence of a check pilot contributed to the deaths of five of the 127 on board. The direct cause of the fire was the failure of a compressor wheel, due to metal fatigue.