What happened
On 30 August, an aircraft was engaged in a private holiday flight that had originated at Moorabbin on 25 August. After several stopovers including Coolangatta and Proserpine, the flight arrived in Cairns. On the day of the accident, the pilot filed an IFR flight plan but failed to include details for the initial segment between Cairns and Biboohra. This error stemmed from a misunderstanding of the enroute chart, as the pilot did not realize that the western tracks originated from Biboohra rather than Cairns.
Although the discrepancy in the flight plan was not caught during submission, the pilot was notified of the correct tracking point during the issuance of his airways clearance. The pilot chose to perform a visual departure rather than using the standard instrument departure profile. Following takeoff instructions that permitted a right turn, the aircraft was seen flying southwest before turning northwest into cloud layers situated between 2000 and 2500 feet above mean sea level. After losing contact with the aircraft, a search was initiated, though poor weather conditions delayed the discovery of the wreckage until the following day.
Findings
Investigation of the wreckage revealed that the aircraft struck the crest of a ridge in the Mt Williams area. At the moment of impact, the aircraft was climbing at approximately five degrees on a west-north-westerly heading. There were no mechanical failures identified as contributing factors to the crash. The investigation concluded that the pilot failed to transition to Instrument Flight Rules after entering cloud cover. Specifically, the pilot did not maintain the required lowest safe altitude of 4500 feet for the segment between Cairns and Biboohra, as the impact occurred at approximately 3250 feet above mean sea level.