Qantas Flight 30

Investigation

The Australian Transport Safety Bureau (ATSB) led the investigation, sending four investigators to Manila to conduct a detailed inspection of the aircraft, with Qantas, the US Federal Aviation Administration, Boeing, the Australian Civil Aviation Safety Authority and the Philippines Civil Aviation Authority also involved.

Soon after the accident, the ATSB announced that air safety investigators found that an oxygen cylinder which was located in the area of the explosion had not been accounted for, but that it was too early to say that an oxygen cylinder could be the cause of the mid-air explosion on QF30. Regardless, the Civil Aviation Safety Authority ordered Qantas to inspect all of its oxygen cylinders and brackets which hold the cylinders on its Boeing 747 fleet. The valve and mounting brackets were found, but not the bottle, number four of thirteen fitted in that bank. A senior investigator, Neville Blyth, reported that the cylinder valve was found inside the cabin, having punched a hole "at least twenty centimetres in diameter" through the cabin floor.

Blyth said that the flight recorders were to be analysed in the Canberra laboratories of the ATSB. However, because the plane had remained airborne and operational throughout the incident, the cockpit voice recorder does not contain records of the initial event itself; its two-hour memory had been overwritten with recordings taking place after this event, during the diversion and landing. The twenty-four-hour flight data recorder does contain data covering the entire incident.

On 29 August, the ATSB gave an update confirming further aspects of the initial investigation. They stated that these initial investigations had found that the aircraft took about five and a half minutes to descend from the decompression event at 29,000 feet to the altitude of 10,000 feet and that it appeared that part of an oxygen cylinder and its valve had entered the passenger cabin, then impacted with the number 2 right door handle, turning it part way. The ATSB noted that there was no risk of the door being opened by this movement, with the door systems performing as designed. All three of the aircraft's instrument landing systems as well as the anti-skid braking system were unavailable for the landing; the pilots subsequently landed the aircraft without using those systems. Most of the oxygen masks deployed in the incident, with 426 out of the 476 deployed being activated by the 346 passengers, pulling them down to activate the flow of oxygen.