The Australian Transport Safety Bureau (ATSB) this week released the final investigation report into the fatal crash of a Yak 9 warbird near Latrobe Valley Regional Airport in 2018.
VH-YIX crashed during an aerobatic flight near Moe, Vic, in September 2018 killing the pilot, who had only recently become the owner of the aeroplane.
One witness said the aircraft had completed a roll and loop before spiralling into the ground. Video from another witness showed the aircraft spinning in a deep nose-down attitude before impact.
According to the ATSB, the pilot had never done aerobatics in the aircraft and would never have experienced the control characteristics displayed by the aircraft whilst in a dive. The pilot was rated for aerobatics above 3000 feet AGL, but radar at nearby RAAF East Sale showed the aircraft was at 2800 feet AMSL during the aerobatic sequence.
ATSB Transport Safety Director Stuart Macleod said the accident highlights the risks inherent with performing low-level aerobatics in high performance aircraft.
“High‑performance aircraft like the YAK 9 transition into a fully developed spin quicker and more forcefully than a typical light training aircraft. It is essential to have sufficient altitude to effectively recover from a spin,” he said.
“Experienced YAK 9 pilots stated that, depending on pilot experience, 5000 to 7000 feet is required to safely recover the aircraft from a developed spin.
The report notes, unlike in most other warbird aircraft, as the airspeed increases during a high-speed dive recovery, in the YAK 9 the effort required to pull back on the control stick reduces.
“This investigation reinforces to pilots performing low-level aerobatics the importance of observing minimum approved operating heights, commensurate with their ability and qualifications, and to engage in regular flight reviews and instruction," the report states.
The investigation report also notes the pilot had conducted aerobatics in a number of warbird aircraft, but had only between five and six hours of flying experience in the YAK 9, and that the accident flight was the pilot’s first in the aircraft in three months.
“With limited experience and recency in flying the YAK 9, the pilot was likely unaware of the aircraft’s unique handling characteristics during aerobatic manoeuvres or spin recovery,” Macleod said.
The ATSB also found that the pilot had failed to secure the rear canopy before the flight, but there was no sign of damage to the airframe resulting from the loss of the canopy. The flight was also done without required documents on board after they were lost during an incident at Dubbo as the aircraft was ferried to Latrobe Valley from Queensland.
On the day of the accident flight, the pilot and instructor had agreed the aircraft was not to be flown without the documents and the pilot said he intended to taxi the aircraft only, but instead took off on the flight that resulted in the crash.
The full report is on the ATSB website.