A phone call minutes before a deadly firefighting crash was a missed opportunity to save the lives of those on board during the preventable tragedy, an investigation has found.
Australian Transport Safety Bureau chief commissioner Angus Mitchell released a report on Thursday into the crash of the twin-engine Gulfstream 695A aircraft near Mount Isa, in the Queensland outback.
"This was a tragic and entirely preventable and unnecessary accident that took three precious lives," he said.
"The dangers of aircraft owners and pilots engaging in practices that deliberately circumvent critical safety defences cannot be underestimated."
The aircraft was conducting aerial fire surveillance operations for bushfires in the state's northwest on November 4, 2024.
There were radio communication issues with the pilot indicating a lack of oxygen in the body, a condition known as hypoxia, before the plane crashed near Cloncurry.
A pilot and two camera operators, including 22-year-old American William Jennings, were on board the plane.
It was operated by AGAIR, a Victoria-based firm that specialises in aerial firefighting.
The bureau found the aircraft had a long-term intermittent defect with its cabin pressurisation system.
AGAIR management had tried to rectify the defect, but they did not formally record it, communicate it to the safety manager, undertake a formal risk assessment or provide explicit procedures to pilots for managing the issue.
"Instead, the ATSB found that there was both encouragement and active participation by company management of continuing to conduct flight operations ... relying on periodic descents to lower altitudes and unsafe use of the emergency oxygen system," Mr Mitchell said.
About 37 minutes before the crash, Airservices Australia staff spoke to AGAIR's head of flying operations by phone to advise they had lost communications with the plane.
During the six-minute call, the AGAIR head was advised the pilot had symptoms of hypoxia.
They were also told air-traffic control had regained communication with the pilot and no longer had concerns for the aircraft.
"At no point ... did the (AGAIR head of flying operations) advise ... that the aircraft had a known intermittent pressurisation defect as it did not occur to them to do so," the report said.
"The conversation to AGAIR was a missed opportunity to communicate critical safety information ... that was directly relevant to the conversation, at a time when (air traffic control) could have taken further action to instruct the pilot to descend to a safe altitude."
The bureau recommended the company seek an independent review of its organisational structure and oversight of operational activities.
AGAIR chief executive Rob Boschen said that "as a responsible operator" it had accepted all of the safety recommendations, many of which had already been implemented.
"Every day, my thoughts remain with the loss that has come about, to our workmates' families, friends, community and our business," he said.
