On 4 September 2000, a chartered Beechcraft 200 Super King Air departed Perth for a flight to the mining town of Leonora, Western Australia.

The aircraft continued flying on a straight north-easterly heading for five hours, before exhausting its fuel and crashing 65 km (40 mi) south-east of Burketown.

[5] The aircraft involved in the crash was a Beechcraft 200 Super King Air, registration VH-SKC, serial number BB-47, manufactured in 1975.

According to the investigation report, several open-microphone transmissions followed, with the sound of background noise from the engines, a person breathing, "one unintelligible syllable," and "two chime-like tones, similar to those generated by electronic devices."

Thirty-one minutes later, Australian Search and Rescue asked the crew of a business jet to approach the Beechcraft.

The investigation report then describes how "the crews of the chase aircraft attempted to contact the pilot of the Beechcraft by radio, but they did not receive a response."

[21] The report stated, "After the aircraft climbed above the assigned altitude of FL250, the speech and breathing patterns of the pilot, evidenced during the radio transmissions, displayed changes consistent with hypoxia.

"[23] The report said due to the damage to the aircraft upon impact with the ground, investigators were unable to conclude if any of the eight aboard used the oxygen system.

"[21] The passengers, the report added, were also likely not wearing their oxygen masks, as there was no noise recorded on the ATC transmissions indicating they were attempting to assist the pilot.

The pilot and passengers were incapacitated, probably due to hypobaric hypoxia, because of the high cabin altitude and their not receiving supplemental oxygen.

The outcome of consultation on the NPRM was that the Civil Aviation Safety Authority did not mandate aural warning of inadequate cabin pressure, and this angered the families of some of the victims.

[3] Instead, the Civil Aviation Safety Authority issued a notice to owners of pressurised aircraft registered in Australia and recommended installation of an aural warning, but did not make it mandatory.

The notice said: "The benefit to your pilots and passengers lies in the reduction in risk of an uncommanded depressurisation leading to an incident or fatal accident.

[31] The Coroner was critical of the poor co-ordination between the ATSB, the Queensland Police, and the Civil Aviation Safety Authority (CASA).

[31] When the air traffic controller responsible for the Beechcraft received the open-microphone transmissions, he alerted his supervisor that he was concerned the pilot could be suffering from hypoxia.

The controller and his supervisor completed the standard checklist which, at the time, did not include a procedure to follow in the case of incapacitation or hypoxia.