Australian Transport Safety Bureau issues interim reports on two Qantas accidents

by B. N. Sullivan

During the past week, the Australian Transport Safety Bureau (ATSB) released interim updates on the investigations of two separate accidents involving aircraft operated by Qantas.

QF 30 depressurization, January 25, 2008

The ATSB issued an interim factual report on the investigation into the depressurization of a Qantas Boeing 747-400 aircraft, registration VH-OJK, on July 25, 2008. That aircraft, operating as Qantas Flight QF30, was en-route from Hong Kong to Melbourne; it diverted to Manila where it made a safe emergency landing. Once on the ground, a large hole in the fuselage was discovered. The ATSB concluded that the failure of an oxygen cylinder damaged the pressure hull and led the depressurization.

The newest report focused on a series of tests carried out on several oxygen cylinders from the same manufacturing lot as the failed cylinder, intended to replicate the failure. The ATSB reports that the "various tests have not been able to replicate the cylinder failure that initiated the accident." The ATSB says:

To date, all pressure tests of the cylinders met or exceeded the relevant safety specifications, with recorded rupture pressures being over twice the maximum working pressure of the cylinders.

The investigation continues, and a final report is expected in early 2010.

Link: Depressurisation – 475 km north-west of Manila, Philippines – 25 July 2008 - Interim Factual No. 2 - 8-page 'PDF' file 

RELATED: Click here to view all posts about Qantas Flt 30 on Aircrew Buzz.

QF 72 in-flight upset, October 7, 2008

The ATSB also issued a second interim factual report on its investigation into an in-flight upset involving a Qantas Airbus A330-303, registration VH-QPA, on October 7, 2008. The aircraft, operating as Qantas Flight QF 72, was en route from Singapore to Perth when it experienced two uncommanded pitch-down events. The flight diverted to Learmonth, Western Australia, where it landed safely.

The new report describes tests carried out in an attempt to discover what caused anomalous behavior of the aircraft's No. 1 Air Data Inertial Reference Unit (ADIRU), which led to the upset. The tests were inconclusive. The ATSB says:

Despite extensive testing and analysis, the reason why the ADIRU started providing erroneous data (spikes) during the 7 October 2008 flight (or the 27 December 2008 flight) has not been identified to date. Nevertheless, the crew operational procedures that were provided by Airbus in October 2008 (and modified in December 2008 and January 2009) significantly reduced the chance of another in-flight upset by limiting the time that a faulty ADIRU could output angle of attack spikes. Airbus is also modifying the FCPC software used in the A330/A340 fleets to prevent angle of attack spikes leading to an in-flight upset.

The ATSB expects to release a final report into this accident in the second quarter of 2010.

Link: In-flight upset 154 km west of Learmonth, WA, 7 October 2008 - 10-page 'PDF' file

RELATED: Click here to view all posts about Qantas Flt 72 on Aircrew Buzz. 

Qantas Flight QF72 In-flight Upset: What happened inside the cabin

The Australian Transport Safety Bureau (ATSB) has issued a preliminary report about an accident last month involving a Qantas A330-300 aircraft in which a number of people were injured. The aircraft, operating as Qantas Flight QF72, was en route from Singapore to Perth, Australia with 10 crew and 303 passengers on board when it experienced two successive in-flight upsets. The aircraft diverted to Learmonth, Western Australia, where it made an emergency landing. One flight attendant and at least 13 passengers were seriously injured and many others experienced less serious injuries, according to the ATSB. Most of the injuries involved passengers who were seated without their seatbelts fastened.

While the newly released report focuses primarily on what happened on the flight deck, and the results of the ATSB's early examination of systems data from the accident aircraft, the report devotes several pages to what happened in the passenger cabin during the emergency, damage to the cabin, and injuries sustained by crew members and passengers.

The upset happened while the aircraft was cruising at 37,000 feet. In describing the sequence of events, the ATSB report notes that at the time the emergency began, the first officer (F/O) had just left the flight deck for a scheduled rest break. The captain and second officer (S/O) were on the flight deck when things began to go awry. The captain asked the S/O to call the F/O back to the flight deck, and while the S/O was on the interphone asking the flight attendant to send the F/O back to the flight deck, "the aircraft abruptly pitched nose-down."

The aircraft descended 650 ft. The crew described the movement as "very abrupt, but smooth. It did not have the characteristics of a typical turbulence-related event and the aircraft’s movement was solely in the pitching plane."

The seatbelt sign was then illuminated and the S/O made a public address for passengers and crew to return to their seats and fasten their seatbelts immediately. A few minutes after the first event, the aircraft commenced a second uncommanded pitch-down event. This time the aircraft descended about 400 ft.

The ATSB report says [pp. 2-4]:

The captain announced to the cabin for passengers and crew to remain seated with seatbelts fastened. The second officer made another call on the cabin interphone to get the first officer back to the flight deck. The first officer returned to the flight deck at 1248. After discussing the situation, the crew decided that they needed to land the aircraft as soon as possible. They were not confident that further pitch-down events would not occur. They were also aware that there had been some injuries in the cabin, but at that stage they were not aware of the extent of the injuries.

[The crew then made an] emergency broadcast to air traffic control, advising that they had experienced ‘flight control computer problems’ and that some people had been injured. They requested a clearance to divert to and track direct to Learmonth, WA. Clearance to divert and commence descent was received from air traffic control.

...The flight crew spoke to a flight attendant by interphone to get further information on the extent of the injuries. The flight crew advised the cabin crew that, due to the nature of the situation, they did not want them to get out of their seats, but to use the cabin interphones to gather the information.

After the cabin crew advised the flight deck of several serious injuries, the crew declared a MAYDAY and made a emergency landing at Learmonth.

Injuries

Quoting again from the ATSB report [p. 5]:

Initial information provided to the Australian Transport Safety Bureau (ATSB) was that 14 people were taken by air ambulance to Perth. Injuries were considered serious, but not life threatening, and included concussion and broken bones. In addition, up to 30 other people attended hospital with possible concussion, minor lacerations and fractures, with up to a further 30 or so people with minor bruises and stiff necks who did not need to attend hospital.

Subsequent information indicates that one flight attendant and at least 13 passengers were admitted to hospital. The nature and extent of the injuries varied considerably, including injuries listed above and spinal injuries.

At the time of the first in-flight upset event, three flight attendants and the first officer were standing in the forward galley and one flight attendant had just left that galley. The first officer and two of the attendants received minor injuries and the other was uninjured. Four of the flight attendants were preparing to leave the crew rest area (four seats located near the Left 3 door), and all received minor injuries. A flight attendant standing in the rear galley received serious injuries.

Information has been obtained from over 10 per cent of the passengers to date. Based on this information, almost all of the passengers who were seated without seatbelts fastened received either serious or minor injuries during the first in-flight upset. Many of these passengers impacted the ceiling panels. Most of the passengers who had their seatbelts fastened were uninjured, although some received minor injuries. Passengers who were standing at the time of the first in-flight upset received either serious or minor injuries.

Damage

There was no structural damage to the aircraft, however the ATSB report had this to say about the passenger cabin [pp. 5-6]:

Inspection of the aircraft interior revealed damage mainly in the centre and rear sections of the passenger cabin. The level of damage varied significantly. Much of the damage was in the area of the personal service units above each passenger seat, and adjacent panels. The damage was typically consistent with that resulting from an impact by a person or object. There was evidence of damage above approximately 10 per cent of the seats in the centre section of the cabin, and above approximately 20 per cent of the seats in the rear section of the cabin. In addition, some ceiling panels above the cabin aisle-ways had evidence of impact damage, and many had been dislodged from their fixed position.

Oxygen masks had deployed from above nine of the seats where there had been damage to overhead personal service units or adjacent panels. Some of the cabin portable oxygen cylinders and some of the aircraft first aid kits had been deployed.

The report includes photos of damage to the ceiling panels above passenger seats, and in the aisle.

Here is the link to the entire document, which is worth reading: AO-2008-070: Preliminary Report - ATSB, Nov. 14, 2008 (43-page 'pdf' file)

RELATED: Click here to view all posts about Qantas Flt QF 72 on Aircrew Buzz.

 

ATSB Preliminary Report on the In-Flight Upset of Qantas Flight QF72 in October

A Preliminary Report has just been released by the Australian Transport Safety Bureau (ATSB) in regard to the in-flight upset of Qantas Flight QF72 on October 7, 2008. Readers will recall that on that date the Airbus A330-300 aircraft was en route from Singapore to Perth, Australia with 10 crew and 303 passengers on board, when it experienced two successive uncommanded pitch-down events. A number of individuals in the passenger cabin were seriously injured. The aircraft diverted to Learmonth, Western Australia, where it made an emergency landing.

About a week after the accident, the ATSB reported that early analysis of the accident aircraft's Flight Data Recorder data, Post Flight Report data and Built-in Test Equipment revealed that an Inertial Reference System fault had occurred within the Number-1 Air Data Inertial Reference Unit (ADIRU 1). Today's report elaborates further on that finding, and also reports on the overall progress of the investigation, which is ongoing.

A summary of important points is contained in a media release issued by the ATSB in conjunction with the publication of the Preliminary Report. Here is a part of that summary:

Examination of flight data recorder information indicates that, at the time the autopilot disconnected, there was a fault in a flight computer system component known as the air data inertial reference unit number 1 (ADIRU 1) which resulted in a number of spurious spikes in ADIRU parameter values. Further spurious parameter spikes continued to influence a number of system failure indications throughout the flight, resulting in frequent failure messages being provided to the crew. The crew completed required actions in response to the messages, but these actions were not effective in removing the spikes or failure indications. The investigation team is continuing to examine the influence of the spikes in ADIRU parameters on the performance of the flight controls.

Most components on modern aircraft, including ADIRUs, are highly reliable and there has only been a small number of occasions where ADIRUs of different types made by varying manufacturers have had some form of failure. It is extremely rare for any such failures to have an effect on an aircrafts flight controls. The ATSB has previously investigated an in-flight upset related to ADIRU failure from a different manufacturer in a Boeing 777 which occurred in 2005 and was traced to a software fault. While a software fault has not been ruled out in the current investigation, it seems unlikely that the two events are linked.

Still ongoing:

• The three ADIRUs will be subject to comprehensive testing at the manufacturer's facilities in the US.
• Review of the ADIRUs' data monitoring capability and management of anomolous ADIRU data, including flight deck indications.
• Review of records of previous occurrences involving ADIRU failures (which did not result in in-flight upsets) and any occurrences where large numbers of spurious messages were generated.
• Subject to the results of the ADIRU testing, examination of other aircraft components may be conducted such as the three flight control primary computers and their software in order to understand why the fault in the ADIRU was able to be translated to flight control movements.

The report goes on to say that, although this is unlikely, possible external sources of electromagnetic interference are being explored and assessed, "including from the Harold E. Holt very low frequency transmitter near Exmouth, WA and from portable electronic devices on board the aircraft."

The investigation of cabin safety issues related to this accident also is still underway. This includes interviews with the cabin crew and seriously injured passengers, and responses to questionnaires "seeking passenger observations during the upset events and asking questions in relation to the use of seatbelts, injuries and the use of personal electronic devices."

The ATSB also noted that a number of important safety actions have already been implemented arising from the investigation to date.

Here is the link to the entire document: AO-2008-070: Preliminary Report - ATSB, Nov. 14, 2008 (43-page 'pdf' file)

RELATED: Click here to view all posts about Qantas Flt QF 72 on Aircrew Buzz.

Systems fault identified in Qantas Flight QF72 in-flight upset accident

The Australian Transport Safety Bureau (ATSB) held another media conference earlier today to provide new details in the progress of its investigation of the Qantas Flight QF72 in-flight upset. In today's media conference, the ATSB described the role a faulty Air Data Inertial Reference Unit played in the accident involving the Airbus A330-300 aircraft.

To review briefly, the accident occurred on October 7, 2008, while Qantas Flight QF72 was en route from Singapore to Perth, Australia with 303 passengers and 10 crew on board. While in cruise at 37,000 ft., the pilots received electronic centralized aircraft monitoring messages in the cockpit relating to some irregularity with the aircraft's elevator control system, and the aircraft departed level flight. According to the ATSB, "the aircraft climbed about 200 feet from its cruising level of 37,000 feet, the aircraft then pitched nose-down and descended about 650 feet in about 20 seconds, before returning to the cruising level. This was closely followed by a further nose-down pitch where the aircraft descended about 400 feet in about 16 seconds before returning once again to the cruising level."

The in-flight upset injured dozens of people in the aircraft's cabin. The crew ultimately declared a MAYDAY and diverted to Learmonth, Australia where they made an emergency landing.

Systems Fault Identified

Today the ATSB update reported a preliminary sequence of events based on further analysis of the accident aircraft's Flight Data Recorder data, Post Flight Report data and Built-in Test Equipment. Quoting from the ATSB's October 14, 2008 statement:

The aircraft was flying at FL 370 or 37, 000 feet with Autopilot and Auto-thrust system engaged, when an Inertial Reference System fault occurred within the Number-1 Air Data Inertial Reference Unit (ADIRU 1), which resulted in the Autopilot automatically disconnecting. From this moment, the crew flew the aircraft manually to the end of the flight, except for a short duration of a few seconds, when the Autopilot was reengaged. However, it is important to note that in fly by wire aircraft such as the Airbus, even when being flown with the Autopilot off, in normal operation, the aircrafts flight control computers will still command control surfaces to protect the aircraft from unsafe conditions such as a stall.

The faulty Air Data Inertial Reference Unit continued to feed erroneous and spike values for various aircraft parameters to the aircrafts Flight Control Primary Computers which led to several consequences including:

• false stall and overspeed warnings
• loss of attitude information on the Captain's Primary Flight Display
• several Electronic Centralised Aircraft Monitoring system warnings.

About 2 minutes after the initial fault, ADIRU 1 generated very high, random and incorrect values for the aircrafts angle of attack.

These very high, random and incorrect values of the angle attack led to:

• the flight control computers commanding a nose-down aircraft movement, which resulted in the aircraft pitching down to a maximum of about 8.5 degrees,
• the triggering of a Flight Control Primary Computer pitch fault.

The crew's timely response led to the recovery of the aircraft trajectory within seconds. During the recovery the maximum altitude loss was 650 ft.

The Digital Flight Data Recorder data show that ADIRU 1 continued to generate random spikes and a second nose-down aircraft movement was encountered later on, but with less significant values in terms of aircraft's trajectory.

At this stage of the investigation, the analysis of available data indicates that the ADIRU 1 abnormal behaviour is likely as the origin of the event.

The ATSB officials went on to say that as far as they can understand, this appears to be a unique event and Airbus has advised that it is not aware of any similar event over the many years of operation of the Airbus.

Action by Airbus

Airbus has issued an Operators Information Telex reflecting the preliminary findings of the ATSB investigation of this accident. The ATSB anticipates that Airbus also will issue Operational Engineering Bulletins and provide "information relating to operational recommendations to operators of A330 and A340 aircraft fitted with the type of ADIRU fitted to the accident aircraft. Those recommended practices are aimed at minimising risk in the unlikely event of a similar occurrence. That includes guidance and checklists for crew response in the event of an Inertial Reference System failure."

ATSB Investigation Continues

The ATSB reported that its investigation is ongoing and will include:

• Download of data from the aircraft's three ADIRUs and detailed examination and analysis of that data. Arrangements are currently being made for the units to be sent to the component manufacturer's facilities in the US as soon as possible and for ATSB investigators to attend and help with that testing, along with representatives from the US National Transportation Safety Board, The French Bureau d'Enquêtes et dAnalyses (BEA) and Airbus.
• In addition, investigators have been conducting a detailed review of the aircraft's maintenance history, including checking on compliance with relevant Airworthiness Directives, although initial indications are that the aircraft met the relevant airworthiness requirements.
• Work is also ongoing to progress interviews, which will include with injured passengers to understand what occurred in the aircraft cabin. The ATSB plans to distribute a survey to all passengers.

The ATSB expects to publish a Preliminary Factual report in about 30 days from the date of the accident.

[Photo Source]

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Qantas Flight QF72 Emergency Landing at Learmonth, Australia

Earlier today, the Australian Transport Safety Bureau (ATSB) held a media conference regarding an in-flight incident on board a Qantas Airbus A330-300 aircraft that caused injuries to dozens of people. The incident occurred yesterday, October 7, 2008, as Qantas Flight QF72 was en route from Singapore to Perth with 303 passengers and 10 crew on board.

Here is what happened, according to the ATSB media statement about Qantas Flight QF72:

The aircraft, which had 303 passengers and 10 crew on board, was in normal level flight at 37,000 ft about 110 nautical miles north of Carnarvon and 80 nautical miles from Learmonth near Exmouth in north-western Australia, when the pilots received electronic centralised aircraft monitoring messages in the cockpit relating to some irregularity with the aircraft's elevator control system.

The aircraft is reported to have departed level flight and climbed approximately 300 ft, during which time the crew had initiated non-normal checklist/response actions. The aircraft is then reported to have abruptly pitched nose-down.

During this sudden and significant nose-down pitch, a number of passengers, cabin crew and loose objects were thrown about the aircraft cabin, primarily in the rear of the aircraft, resulting in a range of injuries to some cabin crew and passengers.

The crew made a PAN PAN emergency broadcast to air traffic control, advising that they had experienced flight control computer problems and that some people had been injured, and they requested a clearance to divert to and track direct to Learmonth.

A few minutes later the crew declared a MAYDAY and advised ATC of multiple injures including broken bones and lacerations. The aircraft landed at about 1530 local time, about 40 minutes after the start of the event.

The ATSB understand that there were 14 people with serious but not life threatening injuries, which included concussion and broken bones who were taken by air ambulance to Perth. In addition, up to 30 other people attended hospital with possible concussion, minor lacerations and fractures, with up to a further 30 or so people with minor bruises and stiff necks etc who did not need to attend hospital. However, these casualty figures are subject to further clarification and confirmation.

All passengers have been now been transported to Perth. Given the nature of injuries, the occurrence is defined as an accident in accordance with the International Civil Aviation Organization definition.

The aircraft's Flight Data Recorder and Cockpit Voice Recorder have been retrieved by investigators and sent to Canberra for examination. In addition, ATSB is carrying out an on-site investigation at Learmonth, where the aircraft remains.

Qantas also issued a statement today with similar information. The Chief Executive Officer of Qantas, Geoff Dixon, also said, "We commend the professionalism of our crew, who ensured the aircraft landed safely in Learmonth."

UPDATE Oct. 9, 2008: The ATSB has issued an update on the Qantas Flight QF72 accident. Today's ATSB media release says, in part:

The aircraft's Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) arrived in Canberra late on Wednesday evening. Downloading and preliminary analysis overnight has revealed good data from both recorders. Data from the FDR has been provided to Qantas, the French Bureau d'Enquêtes et d'Analyses (BEA) and Airbus as parties to the investigation.

While the full interpretation and analysis of the recorded data will take some time, preliminary review of the data indicates that after the aircraft climbed about 200 feet from its cruising level of 37,000 feet, the aircraft then pitched nose-down and descended about 650 feet in about 20 seconds, before returning to the cruising level. This was closely followed by a further nose-down pitch where the aircraft descended about 400 feet in about 16 seconds before returning once again to the cruising level. Detailed review and analysis of FDR data is ongoing to assist in identifying the reasons for the events.

Click here to view the Oct. 9 ATSB media release.

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Dozens injured in Qantas Airbus A330 'sudden in-flight upset'

Dozens of people were injured earlier today, October 7, 2008, when a Qantas A330-300 aircraft experienced what the Australian Transport Safety Bureau (ATSB) referred to as a sudden in-flight upset. Qantas described the event as a sudden change of altitude. According to the ATSB, the crew declared a MAYDAY and diverted to Learmonth, near Exmouth, in Western Australia, where they made an emergency landing at about 13:45 local time.

The aircraft (registration VH-QPA), operating as Qantas Flight QF72, was cruising in level flight en route from Singapore to Perth with 303 passengers and 10 crew on board at the time of the incident. An ATSB media release said that the event resulted in injuries to a number of cabin crew and passengers, primarily in the rear of the aircraft. The ATSB said: "Early reports indicate that three cabin crew and approximately 30 passengers sustained injuries, including about 15 with serious injuries, namely broken bones and lacerations."

The injured were taken to Exmouth Hospital for treatment. Several news media reports said that some of the more seriously injured were later flown to Royal Perth Hospital by the Royal Flying Doctor Service.

Qantas sent two aircraft -- a Boeing 767 and a Boeing 717 -- to Learmonth from Perth to collect passengers and crew.

Best wishes for a speedy and full recovery to all those who were injured.

UPDATE Oct. 8, 2008: Both the Qantas and the Australian Transport Safety Bureau (ATSB) issued statements today with a few more details about the events on Qantas Flight QF72, which the ATSB has now officially classified as an accident: ATSB statement; Qantas statement.