Earlier on the day of the accident the pilot had flown the aircraft to Stanthorpe before returning to Casino at about 1100 EST. He had refuelled the aircraft with approximately 60 litres of Mogas (automotive fuel) immediately prior to departure at about 1250. The aircraft was approved to operate on Mogas.
The last confirmed radio transmission from the pilot after he departed Casino was at 1332 when he reported to Air Traffic Services (ATS) that he was 62 NM from Archerfield, maintaining 4,500 ft. A search was mounted for the aircraft after it was reported overdue on the flight to Archerfield. The following two days of the search were hampered by low dense cloud in the area. Several pilots of overflying aircraft reported hearing transmissions from an emergency locator transmitter in the area of Mt Chingee, near the Queensland-New South Wales border.
Searchers located the wreckage of the aircraft early on the third day of the search, at approximately 2,500 ft AMSL, in densely wooded terrain on the slopes of Mt Chingee. The pilot did not survive the accident. The area where the wreckage was located was known to be a popular poor weather route for VFR traffic through the area.
The Bureau of Meteorology analysed the weather conditions in the area of Mt Chingee on the day of the accident. The analysis indicated that low cloud and probably precipitation would have prevailed at the time of the accident. Residents in the area reported weather conditions consistent with the Bureau of Meteorology analysis.
The Bureau did not conduct an on-site examination for this investigation. An assessment of the aircraft wreckage was carried out using police photographs and video footage. The following assessment is based on the photographic and documented evidence. The aircraft attitude at impact and the damage sustained by the airframe and propeller suggest that the aircraft was in near level flight when it first struck trees. This suggests it was probably under control. The majority of the airframe was severely disrupted by impact forces. The type of torque twisting of both propeller blades and the manner in which the propeller hub separated from the engine, indicate that the engine was developing significant power at impact. The aircraft had a current Maintenance Release that showed no outstanding maintenance requirements.
The last altitude and position report given by the pilot, placed the aircraft at 4,500 ft, approximately 7 NM or about 3 minutes flight time from the accident site. The site was approximately 2,500 ft AMSL.
The pilot usually kept his personal logbook and the aircraft records in the aircraft. None of these records were recovered for examination. Records held by the Civil Aviation Authority show that he held a Private Pilot Licence. He did not hold an instrument rating. His total aeronautical experience was approximately 650 hours. He held a night VMC rating however, it could not be established if the pilot ever exercised the privileges of the rating.
The investigation established that the pilot commonly worked long hours in demanding employment. A Human Factors specialist assessed the pilot's known workload. The specialist advised that the pilot was likely to have experienced sleep deprivation and high workload in the two days preceding the accident. When these factors are combined, fatigue, whether of an acute or a chronic nature, will eventually be experienced. The effects of fatigue on performance vary from individual to individual and may include poor judgement and decision making, increased reaction times, mental haziness or lethargy, and a general decrement in psychomotor performance.
The investigation sought the assistance of a specialist in Aviation Medicine for the interpretation and analysis of the pilot's post-mortem report toxicological results which indicated the presence of prescription drugs. This was done to determine the possible effects these drugs would have on the pilot's ability to safely operate an aircraft. Prescription drugs used alone or in combination may seriously interfere with an individual's ability to safely operate an aircraft, particularly as a single pilot in bad weather. The pilot should have been aware of the potentially serious hazards of using these medications in the flight environment. A review of the CASA aircrew medical examinations of this pilot could find no evidence of any recorded medical problems warranting the use of the drugs described in the toxicology report.