YouTube video from TheFlightChannel

Did this Airbus A330 have a mind of its own? Find out why the A330 operating Qantas Flight 72 suffered a pair of sudden uncommanded pitch-down maneuvers during a flight from Singapore to Perth in October 7, 2008. The plane crash-landed, but very fortunately there were no deaths. All 315 onboard survived, however, 119 were injured. The injuries included fractures, lacerations and spinal injuries -- to several of the passengers and crew. Fourteen people were airlifted to Perth for hospitalization, with 39 others also attending hospital. In all, one crew member and 11 passengers suffered serious injuries, while eight crew and 99 passengers suffered minor injuries.

On 7 October 2008 at 09:32 SST, Qantas Flight 72, with the afore-mentioned 315 people on board, departed Singapore on a scheduled flight to Perth, Western Australia. By 10:01, the aircraft had reached its cruising altitude of around 37,000 feet (11,000 m) and was maintaining a cruising speed of Mach 0.82.

The incident started at 12:40:26 WST, when one of the aircraft’s three air data inertial reference units (ADIRUs) started providing incorrect data to the flight computer. In response to the anomalous data, the autopilot disengaged automatically, and a few seconds later, the pilots received electronic messages on the aircraft's ECAM, warning them of an irregularity with the autopilot and inertial reference systems, and audible stall and overspeed warnings. During this time, the captain began to manually control the aircraft. The autopilot was then re-engaged and the aircraft started to return to the prior selected flight level. The autopilot was disengaged by the crew after about 15 seconds and would remain disengaged for the remainder of the flight.

At 12:42:27, the aircraft made a sudden, uncommanded pitch down manoeuvre, experiencing –0.8 g, reaching 8.4 degrees pitch down and rapidly descending 650 feet (200 m). Twenty seconds later, the pilots were able to return the aircraft to the assigned cruise flight level, FL370. At 12:45:08, the aircraft made a second uncommanded manoeuvre of a similar nature, this time causing an acceleration of +0.2 g, a 3.5 degree down angle, and a loss of altitude of 400 feet (120 m); the flight crew was able to re-establish the aircraft's assigned level flight 16 seconds later. Unrestrained (and even some restrained) passengers and crew were flung around the cabin or crushed by overhead luggage, as well as crashing with and through overhead compartment doors. The pilots stabilised the plane and declared a state of alert, which was later updated to mayday when the extent of injuries was relayed to the flight crew.

The Australian Transport Safety Bureau (ATSB) investigation found a fault with one of the aircraft's three air data inertial reference units (ADIRUs) and a previously unknown software design limitation of the Airbus A330's fly-by-wire flight control primary computer (FCPC).

References

TheFlightChannel: https://www.youtube.com/channel/UCXh6VKhioaeEaMQasii7IfQ
The Australian Transport Safety Bureau (ATSB): https://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-070.aspx
Qantas Flight 72 Wikipedia: https://en.wikipedia.org/wiki/Qantas_Flight_72