Loss of control, Mt Vernon Station, Western Australia, on 1 September 2006, VH-RIL, Cessna 172L

On 1 September 2006, at approximately 1100 Western Standard Time, the pilot of a Cessna C172L aircraft, registered VH-RIL, was conducting a private, visual flight rules (VFR) flight, and together with four passengers (two adults, one child and an infant), departed from 'Bronco', a cattle mustering area on Mt Vernon station, WA. The pilot was to fly to the homestead on the property, a flight of approximately 10 minutes duration.

At the same time, members of the pilot's family and station staff left Bronco in motor vehicles to drive the approximately 30 km journey back to the homestead. Upon their arrival, it was noted that the aircraft had failed to arrive at the homestead. After attempts to contact the pilot by radio failed, a search was conducted, during which the pilot and child passenger were found walking towards the homestead. The pilot, who was disorientated and injured, reported that the aircraft had crashed in bushland adjacent to the homestead airstrip. The child had minor injuries.

After obtaining general directions to the aircraft, the search party were able to locate the aircraft wreckage. On arrival, searchers found a female adult passenger semiconscious with extensive injuries. The male adult passenger and the infant had been fatally injured.

The pilot and female passenger reported that the aircraft had entered severe turbulence during the descent to land, which resulted in a near-vertical nose down attitude of the aircraft approximately 300 to 350 feet above the terrain.

The investigation determined that the pilot had most likely flown through a strong willy-willy and was unable to recover from the in-flight upset. The investigation also found that it was likely that inadequate restraint of some occupants increased the severity of injuries sustained.