Qantas jet probe focuses on exploding oxygen cylinders

Air safety investigators said Sunday that an exploding oxygen cylinder may have been to blame for tearing a huge hole in an Australian Qantas jumbo jet in mid-air, nearly causing a disaster.

Officials said an oxygen back-up cylinder is missing from the aircraft, and ordered the airline to inspect all such bottles on its fleet of Boeing 747s.

The Qantas Boeing 747 was flying from Hong Kong to Melbourne on Friday when an explosive bang led to a sudden loss of air pressure in the cabin.

The plane, which had originated in London and was carrying 365 passengers and crew, plunged 6,000 metres (20,000 feet) before stabilising, then made an emergency landing in the Philippines capital Manila.

There, stunned passengers saw a three-metre (10 foot) hole in the fuselage adjoining the right wing.

An investigator from the Australian Transport Safety Bureau, Neville Blyth, told reporters in Manila that an oxygen back-up cylinder was missing.

"It is too early to say whether this was the cause of the explosion," Blyth said. "But one of the cylinders which provides back-up oxygen is missing."

He said investigators had ruled out terrorism.

"There is no evidence of a security-related event here. Philippine sniffer dogs have inspected the baggage and found no materials of concern."

Blyth would not be drawn on the oxygen cylinder, which is roughly the size of a diver's scuba tank, nor say how many were on the aircraft.

He said the initial inquiry would take two to three days and a preliminary report on the findings should be released in two to three months.

In a statement, Qantas said it would inspect emergency oxygen cylinders on its entire fleet of 747s "as a precaution" by the end of the week.

A spokeswoman for the airline said it had 30 747-400s, including the plane involved in Friday's drama, plus four 747-300s. All 34 aircraft would be affected by the checks, she said.

Peter Gibson, a spokesman for Australia's Civil Aviation Safety Authority, told AFP in Sydney that there were two cylinders "located pretty much exactly where that hole appeared."

"We cannot just say that is the cause but clearly the fact that two oxygen bottles are in that location, and clearly this was damage caused by some sort of outward pressure... means that is a key aspect of the investigation."

He said the cylinders provided emergency oxygen for the flight deck.

If confirmed, Gibson said, it would have implications for all of Qantas's 747s and probably for many others around the world.

He discounted a report that corrosion was to blame, saying that while minor corrosion had been found during a routine check a few months ago, it was in a totally different part of the plane.

Qantas prides itself on its extremely good safety record, and the plane's pilot John Bartels said in a statement that solid training enabled the flight crew to handle the emergency.

"As soon as we realised this was a decompression, I immediately pulled out my memory checklist," Bartels said.

"There were three of us in the cockpit and we all worked together and focused on doing what we had to do to get the aircraft down safely, which is exactly what we are trained to do."

Passengers praised the crew's handling of the incident, but some complained that not all the oxygen masks worked properly.

David Saunders told The Sunday Age paper in Melbourne that the elastic had deteriorated and his mask kept falling, while in some parts of the cabin they failed to drop down at all.

"A guy just went into a panic and smashed the whole panel off the ceiling to get to the mask," he said.

"The kids were screaming and flailing. Their cheeks and lips were turning blue from lack of oxygen."

Qantas defended its procedures, saying the masks had been properly checked, although it added that some systems were probably damaged as a result of the accident.

The Australian Transport Safety Bureau is leading the probe. The US Federal Aviation Administration is also involved, along with manufacturer Boeing.