December 19, 2011
The Australian Transport Safety Bureau (ATSB) issued the final report of their investigation into an in-flight upset accident involving an Airbus A330 in 2008.
On 7 October 2008, an Airbus A330-303 aircraft, registered VH-QPA and operated as Qantas flight 72, departed Singapore on a scheduled passenger transport service to Perth, Western Australia. While the aircraft was in cruise at 37,000 ft, one of the aircraft’s three air data inertial reference units (ADIRUs) started outputting intermittent, incorrect values (spikes) on all flight parameters to other aircraft systems. Two minutes later, in response to spikes in angle of attack (AOA) data, the aircraft’s flight control primary computers (FCPCs) commanded the aircraft to pitch down. At least 110 of the 303 passengers and nine of the 12 crew members were injured; 12 of the occupants were seriously injured and another 39 received hospital medical treatment.
Although the FCPC algorithm for processing AOA data was generally very effective, it could not manage a scenario where there were multiple spikes in AOA from one ADIRU that were 1.2 seconds apart. The occurrence was the only known example where this design limitation led to a pitch-down command in over 28 million flight hours on A330/A340 aircraft, and the aircraft manufacturer subsequently redesigned the AOA algorithm to prevent the same type of accident from occurring again.
Each of the intermittent data spikes was probably generated when the ADIRU’s central processor unit (CPU) module combined the data value from one parameter with the label for another parameter. The failure mode was probably initiated by a single, rare type of internal or external trigger event combined with a marginal susceptibility to that type of event within a hardware component. There were only three known occasions of the failure mode in over 128 million hours of unit operation. At the aircraft manufacturer’s request, the ADIRU manufacturer has modified the LTN-101 ADIRU to improve its ability to detect data transmission failures.
At least 60 of the aircraft’s passengers were seated without their seat belts fastened at the time of the first pitch-down. The injury rate and injury severity was substantially greater for those who were not seated or seated without their seat belts fastened.
The investigation identified several lessons or reminders for the manufacturers of complex, safety‑critical systems.
August 10, 2011
The Civil Aviation Safety Authority has lifted the suspension of Tiger Airways Australia Pty Ltd, effective from Wednesday 10 August 2011.
This follows a thorough investigation by CASA into safety issues within Tiger Airways Australia.
As a result of the investigation and consistent with previous actions taken by CASA, a new set of conditions has been imposed on Tiger Airways Australia’s air operator’s certificate.
These conditions address key areas of operational importance within Tiger Airways and will underpin ongoing improvements in the airline’s safety performance. To continue to operate Tiger must comply with the conditions while they are in place.
Areas the conditions cover include:
- pilot training and proficiency
- pilot rostering and fatigue management
- currency and revision of operational manuals and related documents
- improved change-management processes and the appointment of additional qualified personnel in key positions
- amendments to the airline’s safety management system
Tiger Airways Australia was required to demonstrate it had complied with the necessary safety requirements before it was permitted to resume operations.
These requirements included additional simulator and ground training for Tiger’s pilots.
The number of sectors Tiger Airways may fly is initially limited to a maximum of 18 a day during August 2011. Increased operations after August will be subject to CASA approval.
CASA suspended the air operator’s certificate of Tiger Airways Australia on 2 July 2011.
July 29, 2011
The Australian Civil Aviation Safety Authority (CASA) has given Tiger Airways Australia a set of conditions which can form the basis for the airline resuming operations.
A number of these conditions must be satisfied before any flights can be undertaken. Others require Tiger Airways to take ongoing actions, to CASA’s satisfaction, as the airline builds back up to a normal schedule.
The conditions do not allow for a resumption of operations until CASA is satisfied Tiger is able to do so safely.
If Tiger accepts these conditions, there will be no need for CASA to pursue its application in the Federal Court for an order continuing the suspension of the airline’s operating certificate. In the meantime, Tiger remains suspended and the matter is listed to be heard by the Federal Court on 1 August 2011.
CASA suspended the operations of Tiger Airways Australia on 1 July 2011 due to serious and imminent risk to air safety.
July 6, 2011
The Civil Aviation Safety Authority (CASA) is to seek to extend the suspension of Tiger Airways Australia Pty Ltd.
CASA suspended Tiger Airways Australia’s operations on 2 July 2011 because it believed permitting the airline to continue to fly posed a serious and imminent risk to air safety. On July 6 CASA reported that it was seeking a continuation of the suspension until 1 August 2011 through an application to the Federal Court.
If CASA completes its investigations and determinations before 1 August 2011 and is satisfied Tiger Airways Australia no longer poses a serious and imminent risk to air safety it may be possible for it to resume operations earlier. The suspension of Tiger Airways Australia’s operations remains in place at until either the Federal Court refuses CASA’s application or CASA withdraws it.
CASA is making the application to the Court because investigations into Tiger Airways Australia will not be completed by the end of the initial five working day suspension period.
July 2, 2011
The Civil Aviation Safety Authority (CASA) has suspended the operations of Tiger Airways Australia Pty Ltd with immediate effect from Saturday 2 July 2011.
This action has been taken because CASA believes permitting the airline to continue to fly poses a serious and imminent risk to air safety. The suspension of Tiger Airways Australia follows the issue of a show cause notice to the airline in March 2011.
Taking Tiger Airways Australia’s response to this show cause notice into account, CASA subsequently imposed a number of conditions on the airline’s air operator’s certificate. These conditions required actions to improve the proficiency of Tiger Airways Australia’s pilots, improvements to pilot training and checking processes, changes to fatigue management, improvements to maintenance control and ongoing airworthiness systems and ensuring appropriately qualified people fill management and operational positions.
CASA has been closely monitoring the operations of Tiger Airways Australia throughout 2011, with surveillance undertaken at a range of locations. Since Tiger Airways Australia was served the show cause notice there have been further events raising concerns about the airline’s ability to continue to conduct operations safely. In the circumstances, CASA no longer has confidence in the ability of Tiger Airways Australia to satisfactorily address the safety issues that have been identified.
The suspension is in force immediately for an initial five working days, during which time CASA must apply to the Federal Court for an extension of the grounding. If the Federal Court supports CASA’s application the court can continue the suspension for a period of time which will allow CASA to finalise investigations into the safety matters.
Tiger Airways Australia is a low cost airline which commenced services in the Australian domestic airline market on 23 November 2007. It is a subsidiary of Tiger Airways Holdings, a Singapore-based company, which is owned partially by Singapore Airlines. The main base is at Melbourne Airport. The airline operates a fleet of ten Airbus A320 aircraft.
December 23, 2010
Incorrect unloading can cause an aircraft to pitch up (photo: ATSB)
The Australian Transport Safety Bureau (ATSB) published a study (AR-2010-044) on aircraft loading occurrences from July 2003 to June 2010.
The report documents the number and types of safety occurrences involving loading of high capacity aircraft to raise awareness within the aviation industry of the associated issues.
Incorrect loading of containers, pallets or bags into aircraft can result in them being outside of weight or centre of gravity operating limits, and this may influence aircraft controllability. Most high capacity aircraft loading occurrences are relatively minor, with cargo locks not being raised being the most common. More serious occurrences have involved shifting cargo and unlisted cargo being loaded onto aircraft. Aircraft performance has been affected in a small number of cases, and the result has been rejected takeoff, extra stabiliser trim, or aircraft control difficulties.
The study concluded that the following practices can help to guard against common loading errors:
- Perform cross-checks between the mean aerodynamic chord and stabiliser trim setting, for all LIRs.
- Perform a cross-check of the aircraft weight, as recorded in the aircraft manual – with the load report weight, and ensure the aircraft registration details are correct on the loadsheet.
- Flight crew should not accept a loadsheet while the aircraft is being loaded.
- Incorporate rules within load control software that stop incorrectly configured aircraft loadsheets from being generated.
- Remove off-loaded/rejected containers or loads from next to the aircraft where they can potentially get reloaded in error.
- Use on-board aircraft weight sensors as a cross-check against weight and centre of gravity calculations.
July 24, 2010
The Australian Civil Aviation Safety Authority (CASA) has suspended the air operator’s certificates of Skymaster Air Services and Avtex Air Services. These two charter operators, which share the same ownership, are based at Sydney’s Bankstown airport.
CASA believes allowing Skymaster Air Services and Avtex Air Services to continue to operate while CASA completes further safety investigations poses a serious and imminent risk to air safety.
There have been three serious accidents and a number of incidents involving Skymaster aircraft in the last three months. On 15 June 2010 an aircraft operated by Skymaster crashed at Canley Vale in Sydney, with the pilot and a flight nurse killed. Other accidents include a wheels-up landing and a collapsed nose gear on landing. Incidents include a loss of engine power, fuel flow problems and landing gear malfunctions.
CASA’s decision to suspend Skymaster Air Services and Avtex Air Services is also based on issues relating to the safety culture of the operations, aircraft maintenance control and pilot training.
The suspension of Skymaster and Avtex will end in five business days from Friday 23 July 2010, unless CASA applies to the Federal Court for an order to continue the suspension for up to 40 days. During that time CASA will complete its investigation and determine what further action may need to be taken.
CASA’s actions are separate from the continuing investigation into the Canley Vale accident by the Australian Transport Safety Bureau, the independent Commonwealth transport accident investigator.