Qantas decompression: ATSB media release points to a missing oxygen cylinder

More information are being disclosed about the QF30 as more passengers provide their first hand account of the flight. According to what they recollected, the aircraft did not “plunge” from 29.000 to 10.000 feet. The aircraft took some 10 minutes to descend to the safe altitude. Since the aircraft had to lose some 20.000 feet, it is clear that it descended at a vertical speed of around 2.000 fpm (feet per minute) that is quite normal and for sure not scary. What was less than normal was that the aircraft started the descend with a left turn. After hearing a bang, with gusts through the cabin, with an emergency announcement from the pilot and the oxygen masks dropping from the ceiling, someone thought the aircraft was spiralling uncontrolled towards the sea. However, the turn was induced by the pilots for many reasons:
1) to prevent descending through the levels occupied by other aircraft flying on the same airway
2) to reduce the vertical lift component in order to descend quickly
3) to turn directly inbound Manila (even if I don’t think the pilot had already selected a diversion aerodrome, since the turn was initiated seconds after hearing the boom on the right hand side of the aircraft
The Capt. John Francis Bartels followed the rule of each emergency: “Aviate, Navigate, Communicate”. He fiirst checked if the aircraft was able to fly, he then assumed a heading that would keep the B747-400 far from other traffic (checking the TCAS) and finally broadcasted a Mayday call to the ATC and announced the emergency to the passengers. What worried the passengers was that for some 15 or more minutes after the pilot informed them that they were diverting to the nearest airport, they did not hear anything until the aircraft was stabilized in bound Manila at a safe altitude. However this is normal, since pilots have to concentrate on the emergency and have to bring the aircraft on the ground safely, as soon as possible.

As said the aircraft took 10 minutes to reach breathable air at 10.000 feet. In the meanwhile, some passengers had problems breathing with the oxygen mask because some of them were not well-functioning. Even if some were probably not fed by the oxygen cylinder whose explosion could be the root cause of the hole, perhaps, people was breathing heavily because of the shock caused by the emergency and, despite the oxygen mask (in some cases) was working properly, experienced shortness of breath and feelings of discomfort and fatigue that are common symptoms of the hypoxia.

Dealing with the explosion of an oxygen cylinder as the possible cause of the hole and the subsequent (most probably related) failure of some oxygen masks, the Australian Transportation Safety Board issued today a media release that is publicly available at the following address: http://www.atsb.gov.au/newsroom/2008/release/2008_24.aspx

Qantas Boeing 747-400 depressurisation and diversion to Manila on 25 July 2008
28 July 2008

The ATSB was advised on Friday 25 July of a serious occurrence involving a Qantas aircraft.

The aircraft, a Boeing 747-400 was operating a scheduled passenger service from Hong Kong to Melbourne Australia. At approximately 29,000 feet, the crew were forced to conduct an emergency descent after a section of the fuselage separated and resulted in a rapid decompression of the cabin. The crew descended the aircraft to 10,000 feet in accordance with established procedures and diverted the aircraft to Manila where a safe landing was carried out. The aircraft taxied to the terminal unassisted, where the passengers and crew disembarked. There were no reported injuries.

The ATSB is leading this safety investigation with the assistance of a number of other organisations and agencies, including the Civil Aviation Authority of the Philippines, The National Transportation Safety Board and the Federal Aviation Administration of the USA, the Civil Aviation Safety Authority of Australia and Qantas and Boeing.

The ongoing investigation has confirmed that there is one unaccounted for oxygen cylinder from the bank of cylinders that are located in the area of the breech. There are 13 oxygen cylinders in the bank that are responsible for supplying oxygen to the passenger masks and cabin crew.

Also recovered are a number of parts of components including part of a valve in the vicinity of the breech. However, it is yet to be determined whether these components are part of the aircraft system.

A number of passengers have reported that some of the oxygen masks appeared not to function correctly when they deployed from the overhead modules. The ATSB intends to examine the oxygen system including the oxygen masks.

The ATSB is also intending to interview the aircraft crew including the cabin crew and make contact with all passengers on the flight. All passengers will be surveyed, while those that had reported problems with mask deployment will be interviewed.

The passenger survey should be available in about two weeks.

The ATSB would like to request that any passengers that experienced issues during the flight, or those who photographed or videoed the incident contacts us via email at atsbinfo@atsb.gov.au.

The ATSB would also like to encourage passengers to write down their recollection of events that occurred. This will aid them with the completion of the passenger survey.

The aircraft flight data recorder and the cockpit voice recorder have arrived in Australia. The ATSB will download the recorders at its Canberra facilities over the next few days.

The ATSB will also be examining maintenance records for the aircraft. This will include any airworthiness directives or alert bulletins that may have been issued by the regulators or the manufacturers.

About David Cenciotti 3872 Articles
David Cenciotti is a freelance journalist based in Rome, Italy. He is the Founder and Editor of “The Aviationist”, one of the world’s most famous and read military aviation blogs. Since 1996, he has written for major worldwide magazines, including Air Forces Monthly, Combat Aircraft, and many others, covering aviation, defense, war, industry, intelligence, crime and cyberwar. He has reported from the U.S., Europe, Australia and Syria, and flown several combat planes with different air forces. He is a former 2nd Lt. of the Italian Air Force, a private pilot and a graduate in Computer Engineering. He has written four books.