Accident Overview
A charter flight departed Cairns Airport at 0707 Eastern Standard Time (EST) en route to Hicks Island under Instrument Flight Rules (IFR). The expected flight time was 2 hours.
Flight Details
Shortly after takeoff, the pilot requested an amended altitude of 4,000 ft, indicating he could continue with visual reference to the ground or water. Air Traffic Services (ATS) approved the request. The IFR Lowest Safe Altitude for the initial route sector was 6,000 ft above mean sea level (AMSL).
Approximately 13 minutes after departure, radar contact was lost at a position 46 nautical miles north of Cairns. At the last known radar position, the aircraft was cruising at a ground speed of 180 knots at an altitude of 4,000 ft AMSL.
Wreckage and Witness Observations
An extensive search located the wreckage the following afternoon on the north-western side of Thornton Peak at an altitude of approximately 4,000 ft AMSL. The aircraft was destroyed by impact forces and post-impact fire. The pilot and three passengers received fatal injuries.
Thornton Peak, the third highest mountain in Queensland, has an elevation of 4,507 ft (1,374 metres) as marked on topographic maps. Local residents reported that the mountain was covered by cloud and swept by strong winds for most of the year.
Witnesses observed the aircraft approximately two minutes prior to impact. They reported it was cruising at high speed on a constant north-westerly heading, in a wings level attitude with flaps and landing gear retracted. The engines appeared to sound normal.
Probable Cause
Radar data from ATS and witness reports indicated the aircraft was flying straight and level at constant airspeed, making instrumentation or engine problems unlikely. The aircraft was flown at an altitude insufficient to ensure terrain clearance. Why the pilot continued flight into marginal weather conditions at that altitude could not be established.