The pilot of the Mooney M20J aircraft had planned to take one of his employees from Jandakot to Laverton via Melita Station, where he intended to deliver a small quantity of equipment. The aircraft arrived overhead Melita Station at about 1730 Western Standard Time, approximately 2 hours and 20 minutes after departure. A station hand reported that the aircraft flew over the upwind threshold of the airstrip at a low level and heading in a southerly direction. The aircraft then appeared to fly a downwind leg of a normal circuit before it banked sharply to the left onto an apparent final approach. The station hand then saw the aircraft fly quite close to the ground for about half the length of the airstrip, before adopting a nose-high attitude. The engine noise then increased, although it sounded laboured. When the aircraft was about 100 ft above the ground, he heard the engine noise stop. He then saw the aircraft pitch nose-down and impact the ground in a near vertical attitude. The aircraft was destroyed by the impact and the occupants received fatal injuries. There was no fire.
The aircraft wreckage was located 270 m beyond the northern end of the airstrip and 20 m to the right of the extended centreline. The landing gear was extended, and damage evidence indicated that the propeller was not under power at impact. The flaps were extended; however, their exact setting at impact could not be determined.
The fuel boost pump switch was found in the "off" position. However, it could not be established if the switch was in that position before the accident. The engine-driven fuel pump was damaged during the impact and the investigation was unable to determine if it was functioning correctly prior to the accident. If the engine-driven fuel pump had failed while the fuel boost pump switch was turned off, the engine could have failed due to fuel starvation.
The aircraft was fitted with an emergency locator transmitter (ELT) certified to US Federal Aviation Administration Technical Standard Order (TSO)-C91. Although it appeared to be correctly mounted and connected, The ELT did not activate at the time of the accident. Its instrument panel mounted switch was selected to "arm" and the ELT unit's switch was selected to "auto". The investigation could not determine why the ELT had not operated during the accident. When tested during the investigation, it operated normally.
The Melita Station airstrip, with a useable length of approximately 900 m, was adjacent to the homestead and was aligned approximately north-south. There was no airstrip lighting at Melita; however, runway lighting was available at Laverton.
At the time of the accident, the wind was calm and there was no cloud. The temperature was about 15 degrees Celsius. The station hand stated that although it was twilight, he was able to carry out his tasks without artificial lighting. Airservices Australia advised that the end of daylight on the day of the accident was 1733. The aircraft's flight manual indicated that the aircraft was equipped for night flight.
The pilot held a private pilot licence and a night visual flight rules rating, and was endorsed on the aircraft type. During his aviation medical examination, the pilot indicated that he had a significant family cardiac history. The post-mortem examination established that one of the pilot's coronary arteries was approximately 90 per cent blocked.
The aircraft departed Jandakot with both fuel tanks full. Each tank contained approximately 121 L of useable fuel. Reference to the aircraft's flight manual indicated that fuel usage for the flight should have been between 90 L and 100 L. The pilot's operating handbook (POH) warned that if the selected fuel tank contained less than 30.3 L of fuel, take-off manoeuvres and prolonged sideslips may cause a loss of engine power. Had the engine been drawing fuel from only one tank during the flight from Jandakot to Melita, there would have been approximately 20 L to 30 L of fuel remaining in that tank on arrival at Melita. The nose-high pitch attitude that the aircraft was seen to adopt shortly before the accident might have caused a loss of engine power had the selected fuel tank contained less than 30.3 L. Immediately after the impact, fuel was seen flowing from the aircraft and a strong smell of fuel was evident for some time afterwards. The aircraft's weight and centre of gravity were estimated to have been within the prescribed limits at the time of the accident.
The loss of control during the apparent go-around was consistent with the engine losing power and the aircraft stalling at a height from which recovery was not considered to be possible. The POH warned that the aircraft might lose up to 290 ft of altitude during a stall at maximum weight.
The investigation was unable to establish the reason for the engine failure and did not identify any pre-existing aircraft defects that might have influenced the circumstances of the accident. The significance of the effects of the pilot's medical condition could not be determined.