Australian Transport Safety Bureau investigators found that the operator of two livestock mustering helicopters which collided soon after take-off on July 25, 2024 had allowed pilots to arrange their own separation practices.
The pilots of four Robinson R22s had planned to take off from the Mount Anderson Station homestead, in WA's Kimberley region, to fly to a nearby mustering site.
Shortly after take-off, two helicopters flown by the lead pilot and another experienced mustering pilot, collided. Both aircraft crashed, killing the pilots.
The investigation established that the helicopters collided during their initial climb, after the lead helicopter had manoeuvred to the right.
"Neither pilot detected their converging flight paths before the collision," Chief Commissioner Angus Mitchell said.
"The wreckage examination indicated that at the point of collision, the lead helicopter may have been in a blind spot for the second helicopter."
The investigation examined what actions the helicopters' operator, Pearl Coast Helicopters, took to manage aircraft separation.
"The tools used by the operator to consider and manage operational risk were not tailored to their main business of aerial mustering," Mr Mitchell said.
"The risk of collision had not been identified in operational risk assessments, and the operator's manuals did not provide documented procedures to ensure pilots establish and maintain adequate separation between helicopters."
Company pilots were permitted to arrange their own separation based on personal preference.
"Pilots routinely flew with reduced vertical and lateral separation, and over time this became an accepted operating preference," Mr Mitchell said
The accident was a demonstration of the need for risk management to identify, assess and mitigate risks.
"Aerial mustering plays a critical role in Australia's agricultural sector," Mr Mitchell said.
"This tragic accident should serve as a trigger for all mustering operators to consider their risk management practices, and whether they have scaled them adequately for their operation."
The accident was also a reminder of the fallibility of "see-and-avoid" as a primary means of identifying and managing the threat of collision, Mr Mitchell said.
