The Airbus A330-300 was flying from Singapore to Perth when it suddenly plunged thousands of feet, leaving more than 50 people injured.
Thousands of feet? Absolutely not. From the Australian Transport Safety Bureau
Interim Factual Report:
At 0932 local time (0132 UTC) on 7 October 2008, an Airbus A330-303 aircraft, registered VH-QPA, departed Singapore on a scheduled passenger transport service to Perth, Australia. On board the aircraft (operating as flight number QF72) were 303 passengers, nine cabin crew and three flight crew. At 1240:28, while the aircraft was cruising at 37,000 ft, the autopilot disconnected. From about the same time there were various aircraft system failure indications. At 1242:27, while the crew was evaluating the situation, the aircraft abruptly pitched nose-down. The aircraft reached a maximum pitch angle of about 8.4 degrees nose-down, and descended 650 ft during the event. After returning the aircraft to 37,000 ft, the crew commenced actions to deal with multiple failure messages. At 1245:08, the aircraft commenced a second uncommanded pitch-down event. The aircraft reached a maximum pitch angle of about 3.5 degrees nose-down, and descended about 400 ft during this second event.
At 1249, the crew made a PAN urgency broadcast to air traffic control, and requested a clearance to divert to and track direct to Learmonth. At 1254, after receiving advice from the cabin of several serious injuries, the crew declared a MAYDAY. The aircraft subsequently landed at Learmonth at 1350.
One flight attendant and 11 passengers were seriously injured and many others experienced less serious injuries. Most of the injuries involved passengers who were seated without their seatbelts fastened or were standing. As there were serious injuries, the occurrence constituted an accident. [...]
Two other occurrences have been identified involving similar anomalous ADIRU behaviour, but in neither case was there an in-flight upset.
Peak g loads during the upset were +1.56 g and -0.80 g. Subsequent examination revealed no structural damage to the aircraft. It is possible that a similar ADIRU problem could result in a substantially more difficult upset that the crew were unable to recover, although following the accident discussed here, Arbus sent out Operations Engineering Bulletins to all operators with potentially affected aircraft, detailing what to do if the problem occurred.