The pilot of a Yak-52 warbird aircraft that crashed into the water near South Stradbroke Island in June 2019 was conducting low-level aerobatics at less than 500 feet before the crash, despite not being qualified to do so.
The pilot only held an endorsement to conduct aerobatics at no less than 3,000 feet, according to the Australian Transport Safety Bureau, which investigated the incident.
According to the ATSB, the ex-military trainer aircraft departed Southport Airport, on Queensland’s Gold Coast, on the morning of 5 June 2019 for a private aerobatic flight expected to last about 30 minutes.
When the aircraft did not return, a search and rescue operation commenced.
Part of the aircraft’s propeller was located on South Stradbroke Island later that afternoon, however, the rest of the aircraft was not recovered until days later, after being located in the waters near Jumpinpin channel.
The pilot and his passenger were both fatally injured in the crash.
“The ATSB’s investigation established that prior to the accident, the pilot had conducted a number of aerobatic manoeuvres below 500 feet above ground level,” ATSB director of Transport Safety Dr Stuart Godley said.
While the ATSB could not say with certainty that the pilot was attempting an aerobatic manouevre immediately before the crash, due to an absence of data, witnesses did see the plane “loop, cut right, and dive below the tree line”.
“During the accident flight and previous flights, the pilot conducted low-level aerobatics without having completed the required training or having the appropriate endorsement to do so,” Dr Godley said.
“This would have potentially limited the pilot’s appreciation of the inherent risks associated with low-level aerobatics.”
Research shows that pilot perceptions of risk may decrease with repeated successful outcomes, and if a pilot has a history of flights without incident, then they may perceive that they have a lower likelihood of an adverse outcome based on their prior incident-free experiences, Godley noted.
“This accident highlights the inherent risks associated with performing low-level aerobatics where there is a reduced safety margin for recovery,” Godley said.
“Even more so, it demonstrates the importance of being suitably-trained and qualified to conduct these operations.”
The investigation noted that people with aviation experience and knowledge had witnessed the pilot undertake previous low-level aerobatic flights, and while it appears some attempts have been made to educate the pilot about risky behaviour, no incidents had been formally reported.
“We encourage witnesses, particularly those within the aviation industry, to report any concerns regarding unsafe behaviours through mechanisms such as confidential reporting systems, such as the ATSB’s own REPCON, or the Civil Aviation Safety Authority’s online reporting portal,” Godley said.
“Confidential reporting provides a means to escalate concerns about pilot behaviour while providing protections for the source of the report.”
Godley also noted that the investigation found a pre-existing fatigue crack in the aircraft’s elevator bellcrank, which had the potential to fail in-flight, leading to a loss of control.
Although this crack did not contribute to the accident flight, the finding prompted the ATSB in November 2020 to issue a safety advisory notice to Yak-52 maintainers and owners, emphasising the importance of dye penetrant inspections to remove defective elevator bellcranks from service.