Accident Overview
Late in the afternoon of 30 August 1972, two aircraft were conducting an aerial topdressing operation at Clayton Station. One pilot observed the other aircraft operating normally, but moments later saw smoke and flames on the side of a ridge in the working area. Realizing an accident had occurred, the pilot immediately returned to the airstrip and raised the alarm.
The aircraft, registration ZK-CFQ, had struck the ground with its port wingtip while making a 180-degree right-hand turn within the confines of a valley. Physical evidence showed the plane was banked at an angle of 68 degrees when the wingtip touched the slope. The aircraft was destroyed by impact forces, and fuel from a ruptured tank ignited, completing the destruction. Evidence indicated the engine was producing high power at the moment of impact. The all-up weight and center of gravity were found to be well within permitted limits.
Investigation Findings
The other pilot reported seeing an interruption in the flow of fertilizer during the final sowing run, but there was no sign of a blockage in the hopper outlet. The hopper was empty at the time of the accident. Weather conditions were perfect for aerial topdressing, with ceiling and visibility unlimited (CAVU) and still air.
An autopsy revealed that the 34-year-old pilot had received no fatal injuries from the impact, but there was evidence of coronary occlusion due to arteriosclerotic heart disease. It was concluded that the pilot had died from a heart attack and traumatic hypoxia. It was not clear if the heart attack occurred before or at the time of impact.
Probable Cause
The official probable cause was stated as loss of control at low height for undetermined reason. However, the steep angle of bank so close to the ground suggests the pilot became incapacitated and lost control of the aircraft.