Qantas Flight 72

Qantas Flight 72
Company type	Scheduled commercial flight
Industry	Aviation
Headquarters	Sydney, Australia
Parent	Qantas Airways

Qantas Flight 72 (QF72) was an Airbus A330 scheduled service traveling from Singapore Changi Airport to Perth Airport. On 7 October 2008, the plane executed an emergency touchdown at Learmonth Airport, near Exmouth, Western Australia, following abrupt and uncommanded nose-down movements. These sudden maneuvers resulted in significant injuries—including fractures and spinal trauma—among both passengers and crew. Emergency responders at Learmonth included the Royal Flying Doctor Service of Australia and CareFlight. Fourteen individuals were airlifted to hospitals in Perth, while thirty-nine others received treatment locally. Overall, one crew member and eleven passengers suffered serious injuries, with eight crew members and ninety-nine passengers sustaining minor harm.

The Australian Transport Safety Bureau (ATSB) investigation determined that a malfunction in one of the aircraft’s three air data inertial reference units (ADIRUs), combined with an unrecognized software limitation in the Airbus A330’s fly-by-wire flight control primary computer (FCPC), triggered the incident.

Background

The aircraft involved was an Airbus A330-303, a twin-engine turbofan registered as VH-QPA. Commanding the flight was Captain Kevin Sullivan (aged 53), an ex-US Navy aviator (1977–1986) now based in Australia. The cockpit team also included First Officer Peter Lipsett and Second Officer Ross Hales. Captain Sullivan had accumulated 13,592 total flight hours (2,453 on the A330), Lipsett had 11,650 hours (1,870 on the A330), and Hales had 2,070 hours (480 on the A330). In addition to the three pilots, nine cabin crew members were on board alongside 303 passengers, making a total of 315 occupants.

Flight details

At 09:32 Singapore Standard Time (SST) on 7 October 2008, Qantas Flight 72 departed from Changi Airport bound for Perth with all 315 aboard. By 10:01 SST, it had reached cruising altitude around FL370, maintaining Mach 0.82.

The event commenced at 12:40:26 Australian Western Standard Time (AWST) when one of the aircraft’s three ADIRUs began transmitting erroneous data to the flight control system. This caused an automatic disengagement of the autopilot. The flight deck crew received multiple electronic alerts indicating autopilot and inertial reference system faults alongside contradictory stall and overspeed warnings. The captain took manual control and briefly reactivated autopilot for approximately fifteen seconds before disengaging it for the remainder of the journey.

At 12:42:27 AWST, the aircraft experienced an uncommanded nose-down pitch resulting in −0.8 g acceleration, an 8.4° downward angle of attack, and a rapid altitude loss of . The pilots managed to recover to FL370 within twenty seconds. A second unexpected pitch-down occurred at 12:45:08 AWST, producing +0.2 g acceleration, a 3.5° nose-down attitude, and a further altitude decrease; level flight was reestablished within sixteen seconds. Passengers and crew who were not secured were violently thrown about or struck by overhead bins and compartment doors. Following stabilization of the aircraft, the flight crew declared a state of alert that was later escalated to mayday as injury reports surfaced.

Investigation

The inquiry led by the Australian Transport Safety Bureau (ATSB) received assistance from the Australian Civil Aviation Safety Authority, Qantas Airways, France’s Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA), and Airbus. Data from both the flight data recorder and cockpit voice recorder were shared with BEA and Airbus for detailed examination.

The faulty ADIRU unit, produced by Northrop Grumman, was sent to the United States for further evaluation. On 15 January 2009, the European Aviation Safety Agency (EASA) issued an emergency airworthiness directive addressing malfunctions affecting A330 and A340 aircraft equipped with Northrop Grumman ADIRUs that could respond incorrectly to defective inertial reference inputs.

An initial ATSB report identified a defect in ADIRU number one as the probable cause; this unit began providing inaccurate information to other aircraft systems. Early symptoms included:

False and conflicting stall and overspeed warnings
Loss of altitude readout on the captain’s primary flight display
Multiple alerts from the electronic centralized aircraft monitor system

Approximately two minutes later, ADIRU no. 1 generated erroneous angle of attack (AOA) readings that were excessively high, which led to:

Flight control computers commanding a nose-down pitch reaching roughly 8.5 degrees
Activation of a fault alert in the flight-control primary computer (FCPC)

This investigation revealed critical weaknesses in sensor system reliability impacting aviation safety and instigated regulatory measures influencing Airbus operations involving aircraft fitted with Northrop Grumman ADIRUs.

FCPC design shortcomings

Angle of attack (AOA) is a vital flight parameter, and fully automated flight control systems, such as those on the A330/A340, depend heavily on precise AOA measurements. These aircraft employed three ADIRUs to ensure redundancy, with the Flight Control Primary Computers (FCPCs) cross-checking all three AOA inputs for consistency. Typically, the FCPCs averaged AOA 1 and AOA 2 values. If one reading deviated markedly, the system would replace it with a stored value for a duration of 1.2 seconds. However, the FCPC algorithm was not equipped to manage multiple rapid spikes in AOA 1 or AOA 2 occurring within that 1.2-second window—particularly if a new spike emerged just as the memorised value period concluded.

During the development phase of the A330/A340 flight control system in 1991–1992, extensive safety protocols—including peer reviews, system safety assessments (SSA), and comprehensive testing—were implemented but failed to identify this particular FCPC design vulnerability.

The ADIRU failure mode involved had not been previously recognized and was not detected by the manufacturer’s SSA. In summary, Airbus’s design, verification, and validation processes did not fully anticipate frequent spurious data spikes originating from the ADIRU units.

Airbus reported no earlier incidents of this nature and subsequently issued an operators’ information Telex containing procedural guidance and checklists intended to mitigate risks should similar events occur.

Investigation findings

Detailed examination of the flight data recorder (FDR), FCPC software, and ADIRU hardware revealed that the ADIRU’s central processing unit corrupted AOA information by mistakenly reassigning an altitude data word. Specifically, binary data corresponding to an altitude of 37,012 feet was incorrectly interpreted as an angle of attack of 50.625°. This erroneous high AOA reading activated the FCPC’s high-AOA protection mode, which instructed the electrical flight control system (EFCS) to lower the aircraft’s nose.

Possible causes examined

The inquiry explored various potential causes including software defects, data corruption, hardware malfunctions, electromagnetic interference, and bit flips induced by secondary cosmic rays. Although no definitive root cause was established, evidence pointed to a marginal hardware vulnerability that made the units susceptible to an environmental trigger. The Australian Transport Safety Bureau (ATSB) assessed suggestions that interference from the Naval Communication Station Harold E. Holt or passenger electronic devices caused the fault as "extremely unlikely."

Summary

The ATSB’s conclusive report dated 19 December 2011 attributed the incident to a combination of a design limitation within the Airbus A330/A340 FCPC software and a malfunction in one of the three ADIRUs onboard. This rare combination generated multiple erroneous AOA spikes, causing the FCPCs to issue unintended nose-down commands.

Related Qantas Flight 71 event

On 27 December 2008, a Qantas A330-300 operating between Perth and Singapore encountered an autopilot disengagement alongside an alert indicating failure of ADIRU number 1 approximately northwest of Perth at flight level 360. The flight crew applied Airbus’s updated procedures derived from lessons learned in the prior accident and returned safely to Perth. The ATSB included this occurrence in its ongoing investigation into Flight 72. This incident revived media speculation regarding possible interference from the Harold E. Holt communication facility, leading to calls by the Australian and International Pilots Association for restrictions on commercial flights near that location until further clarity is achieved. The facility’s management maintained that interference was "highly, highly unlikely."

Aftermath

Emergency responders and medical personnel acted swiftly following the incident. The Royal Flying Doctor Service alongside CareFlight transported 20 passengers with severe injuries to Perth for advanced care, while others were treated at Exmouth Hospital. To support the situation, Qantas sent two aircraft from Perth carrying medical teams and customs officials to assist and facilitate the return of uninjured travelers. Passengers who opted not to travel that evening were provided lodging in Exmouth.

The aircraft VH-QPA experienced only minor damage, underwent repairs, and was subsequently reinstated into Qantas' operational fleet.

Compensation

Qantas extended compensation offers to all affected passengers, which included full reimbursement for disrupted travel plans, travel vouchers equivalent to a round-trip fare to London in their original class, and coverage for medical costs. Additional claims were evaluated on an individual basis, with several passengers initiating legal proceedings against Qantas. Among them, a couple alleging they were restrained during the event disputed the airline’s management of their claims.

Flight attendant Fuzzy Maiava, who suffered permanent injuries, rejected a compensation proposal of NZ$35,000 from Qantas and chose to join a class-action lawsuit targeting Airbus and Northrop Grumman. The lawsuit was dismissed due to procedural issues, leaving Maiava without any settlement; he remained unable to work or operate a vehicle.

Dramatisation and book

The Qantas Flight 72 event was dramatized in 2018 on the Canadian television series Mayday, specifically in season 18, episode 7 titled "Free Fall." In May 2019, Kevin Sullivan, the flight’s captain, authored a book recounting the incident for an Australian audience. The following month, the Australian program Sunday Night broadcast a feature containing firsthand accounts from passengers and crew members such as Sullivan and flight attendant Fuzzy Maiava, alongside insights from Chesley "Sully" Sullenberger, captain of US Airways Flight 1549. Despite these disclosures, Qantas prohibited current employees from publicly discussing the event; this included off-duty customer service manager Diana Casey, who had aided others despite sustaining injuries herself.

External links