• The accident site of VH-JWB showing the long line and Bambi bucket. (ATSB)
    The accident site of VH-JWB showing the long line and Bambi bucket. (ATSB)

The Australian Transportation Safety Bureau (ATSB) has targeted a medical condition as the potential cause of the fatal crash of a Kawasaki BK117 on firefighting duties in 2018.

BK117 VH-JWB was deployed to a fire west of Ulladulla NSW in August 2018 when the long line and Bambi bucket slung beneath the helicopter became caught in trees, causing the aircraft to impact the ground. The pilot, the only person on board, was killed in the crash.

In the final investigation report released today, the ATSB said the pilot had re-filled the bucket from a nearby dam and was returning to the fire site when he became incapacitated due to a heart condition. The aircraft deviated from the planned track, which resulted in the bucket entering a treeline.

"The pilot’s post-mortem identified a focus of acute inflammatory change in the heart muscle, a condition known as lymphocytic myocarditis,” ATSB Director Transport Safety, Stuart Macleod said. “This condition is capable of causing sudden impairment or complete incapacitation.

"The pilot is unlikely to have known they suffered from this condition. There are no risk factors for the development of this condition and it cannot be detected by medical screening.”

The pilot’s post-mortem identified coronary heart disease which is also capable of causing sudden impairment and incapacitation. However, despite the pilot suffering from these two heart-related conditions, the ATSB couldn't find enough evidence to state they were definitely the cause.

The aircraft struck the ground inverted, resulting in the fuselage being compressed, a situation the ATSB has said was not surviveable. However, evidence from the first responders showed the upper torso restraint (UTR) was worn incorrectly at the time of the accident.

“Although on this occasion the accident was unsurvivable, the use of such a shoulder harness restraint generally reduces the likelihood of fatal head injuries,” Macleod said.

“Pilots are reminded to always use UTRs if they are fitted to the aircraft.”

The full report is on the ATSB website.

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