What happened
On 25 July 2024, a mustering operation involving four helicopters was underway along the Fitzroy River, northwest of Mount Anderson Station near Curtin, Western Australia. The operation involved two Robinson R22 helicopters, registered as VH-HQH and VH-HYQ, which departed from a clearing near a homestead. The flight plan intended for these two aircraft to track west to rendezvous with two other helicopters before following the river.
Shortly after takeoff, while flying at an altitude of approximately 150 ft, the two aircraft collided. The impact caused an immediate loss of control, and both helicopters struck the terrain. The pilots of both aircraft sustained fatal injuries.
The investigation
Investigators examined the wreckage and analyzed audio recordings from a nearby video source. The examination of the debris revealed that at the moment of impact, the aircraft were flying almost side-by-side, with VH-HYQ positioned approximately 2 m behind and 2.5 m lower than VH-HQH. This positioning deviated from the established plan, which required the second helicopter to follow the first in a sequence.
Audio analysis of a recording made during the event indicated a change in sound frequency, suggesting one helicopter was maneuvering away from the microphone. Based on the relative positions of the aircraft, investigators determined that VH-HQH was likely turning right, placing the aircraft on converging flightpaths.
While twilight conditions were present, the investigation found that the pilot of VH-HQH should have been able to see VH-HYQ against the sky, and the use of position lighting and high-visibility rotor blade paint likely aided visibility. No mechanical defects or prior contact with obstacles were identified as contributing factors.
Findings
- The aircraft were not maintaining the agreed-upon separation sequence.
- The collision was likely caused by the aircraft flying on converging tracks following a turn by the lead helicopter.
- The pilot of the lead aircraft may have been distracted by communications with ground-based helicopters, while the pilot of the trailing aircraft may have been focused on assessing risks from helicopters preparing to lift from the ground.
- There was no evidence of mechanical failure or external obstructions such as wires or vegetation prior to the impact.