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Final Report

Summary

What happened

On 12 July 2016, the pilot of a Cessna 150 aircraft, registered VH-RXU, was conducting cattle spotting operations at New Crown Station, about 270 km south-east of Alice Springs, Northern Territory. The aircraft was observed conducting turning manoeuvres over the cattle at a reported altitude of about 500 ft.

A stockman recalled that, immediately preceding the accident, the pilot was directing them by radio to a breakaway herd of cattle in a nearby riverbed. The stockman observed the aircraft in a right turn moments before hearing it impact the ground, meters from their position.

For reasons that could not be determined, the pilot lost control of the aircraft and was unable to arrest the descent before the aircraft impacted the ground heavily. The pilot was the sole occupant on-board the aircraft and was fatally injured. The aircraft sustained significant damage.

What the ATSB found

The pilot lost control of the aircraft after commencing a right turn. While the actual events preceding the loss of control could not be concluded, the aircraft was likely operated at a slow airspeed with reduced stall margins. In the absence of other physical evidence, it was possible that control inputs made by the pilot induced a stall and incipient spin at an altitude that was not recoverable.   

The pilot was not using the full lap/sash occupant restraint at the time of impact. The extent of injuries sustained by the pilot during the impact probably would have reduced if the sash portion of the restraint were used. This would likely have improved pilot survivability.

The fuel type used by the operator and pilot was not approved for use in VH-RXU. Although probably not contributing to the loss of control, it increased the risk of carburettor icing and formation of vapour in the fuel system. 

What's been done as a result

The operator advised that since the accident, only the grade/type of fuel approved for use in the aircraft would be used.

Safety message

Turning manoeuvres at or close to the aircraft’s critical angle of attack, if mishandled, can lead to a stall that may result in the aircraft entering a spin. Recovery from this condition will take a considerable amount of altitude, dependant on the speed of response by the pilot and the use of appropriate control inputs.

Pilots need to assess the operational risks associated with not using full lap/sash restraints. The appropriate use of these restraints would prevent more serious deceleration injuries in the event of an accident.

To ensure engine performance, pilots and operators must ensure that the fuel used is of the correct grade/type for the aircraft, and is free of contaminants.

 

The occurrence

Context

Safety analysis

Findings

Sources and submissions

 
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