Final Report Blames Cabin Pressure Issue for Deadly Queensland Plane Crash

The final report into a fatal outback plane crash in Queensland has revealed the tragedy was caused by a known pressurization defect, depriving the pilot of oxygen and leading to a loss of control. The accident, which killed all three people onboard, has been deemed “entirely preventable” by the Australian Transport Safety Bureau (ATSB) on June 18, 2025.

The Gulfstream 695A twin-turboprop aircraft, operated by Victorian company AGAIR, took off from Toowoomba on November 4, 2023, en route to photograph fire zones near Mount Isa. It crashed 55 kilometers southeast of Cloncurry and was consumed by fire after impact. Among the victims was 22-year-old American mechanical engineer William Jennings.

ATSB Chief Commissioner Angus Mitchell confirmed the pilot was suffering from hypoxia when the crash occurred, due to the aircraft’s unreliable pressurization system—an issue known to the operator for several months.

“The aircraft’s pressurization system was not reliably maintaining the required cabin altitude,” Mitchell said. “This led some company pilots to use unsafe workarounds, including flying at lower altitudes and misusing emergency oxygen systems.”

The investigation found that while AGAIR management was aware of the defect and had attempted repairs, they failed to formally record the issue, assess the risk, or provide clear guidance to pilots. Crucially, the problem was not reported to air traffic control.

Flight data revealed the pilot had descended from 28,000 feet to 15,000 feet before climbing again shortly before the crash. As the aircraft approached Cloncurry, both power levers were likely reduced to initiate another descent, but the plane lost speed, entered a steep descending turn, and went into an unrecoverable spin.

“Independent speech analysis confirmed signs of hypoxia, and it’s possible the pilot lost consciousness,” Mitchell said. “This tragedy could have been prevented with proper documentation, safety protocols, and communication.”

The aircraft had previously operated in South Africa from 1982 to 2014 before being brought to Australia. Repairs were made at that time, but pressurization issues persisted.

In the aftermath, Australia’s Civil Aviation Safety Authority (CASA) has pledged to evaluate oversight procedures and implement further improvements to surveillance and risk detection.

An online fundraiser raised over AUD $142,000 (USD $95,140) to repatriate William Jennings’ remains. His family described him as a “bright light extinguished too soon”—a recent Northeastern University graduate with a passion for hiking, nature, and engineering.

The identities of the other two victims have not yet been made public.

AGAIR CEO Rob Boschen responded to the report, saying the company had accepted all ATSB recommendations, though not all have been fully implemented.

“Every day my thoughts remain with those we lost,” Boschen said. “AGAIR is committed to a strong aviation safety culture and continues to work through the remaining safety improvements.”

Despite the findings, Boschen noted that the full causes of the crash are still under internal review.

Sources: AirGuide Business airguide.info, bing.com, abc.net.au