CIRCUMSTANCES: "On 16 July 1983, the pilot/owner of the aircraft, Mr Elsing, flew it from Griffith, its home base, to Hobart with Mr and Mrs Twilley as passengers. The purpose of the trip was an overnight visit to Hobart, with a return to Griffith on 17 July. Mrs Twilley suffered earache and airsickness on the flight to Hobart and decided to return on an airline flight. Initially her husband was to accompany her but finally decided to return on VH-WJC. Prior to departing from Hobart the pilot supervised the refuelling of the aircraft and had 344 litres added to the fuel tanks. After the refuelling he personally checked the security of the fuel tank caps. The pilot submitted a flight plan to the Hobart Briefing Office for a private category flight from Hobart to Moorabbin, tracking via Launceston and Wonthaggi. The plan indicated that the flight would be conducted under Instrument Flight Rules (IFR) at Flight Level 120 (12000 feet on standard atmospheric pressure of 1013.2 millibars), with two persons on board. The flight plan showed that the aircraft had a fuel endurance of 220 minutes, and carried an Emergency Locator Beacon (ELB) and life jackets. There was no indication that a life raft was carried. The aircraft departed Hobart at 1352 hours and the flight apparently progressed normally until 1452 hours when the pilot advised Launceston Air Traffic Control, ""Er Whiskey Juliet Charlie we seem to have been in trouble with er fuel here the red er warning light comes and the gauge is down .."". At 1454 hours the pilot transmitted a Mayday call, indicating that he was descending from Flight Level 120 to track to Bass (a position reporting point); present position was 85 nautical miles (nm) from Launceston and he would be making a controlled ditching. Launceston Control suggested a diversion to Devonport but the pilot did not respond to the suggestion. At 1455 The pilot reported, ""We have lost an endurance of more than two two zero in flying time of seven zero minutes and when the warning light goes on this aircraft we have got three zero minutes flying left ....."". At 1456 the pilot advised that he intended to remain on track and make an emergency descent at 2000 feet per minute ""in case the pressurisation gets lost"". At that time the pilot reported his position as 92 miles from Launceston and indicated that he would stay on track and fly low ""in case we cut out"". At 1457 he asked if there was any advice available from Aero Commander experts on how to ditch the aircraft, however no information on the matter was immediately available. At 1459 Launceston Control established that the pilot intended descending to 500 feet to ""observe the situation"". The pilot also advised that the aircraft was ""DME Wonthaggi nine five"", i.e. the aircraft was 95 nm from the Wonthaggi Distance Measuring Equipment (navigation aid). In response to further enquiries, the pilot reported that the aircraft had left 4000 feet on descent and the remaining flying time was ""none whatsoever theoretically"". The last recorded transmission from the aircraft was at 1501 45 when the pilot confirmed that there were two persons on board. There was no indication from the pilot, at any time, that the fuel supply had been exhausted or that either engine had failed. It was estimated that the aircraft ditched at about 1505 hours, at an approximate position of 81 nm from Wonthaggi on the planned track. Searching aircraft subsequently sighted a fuel slick and a survivor in the water, however, contact with this person was lost before rescue helicopters and ships reached the area. No trace has since been found of the aircraft or its occupants. Subsequent investigation indicated the loss of fuel reported by the pilot was probably the result of a malfunction in the fuel system, rather than a spurious indication of fuel remaining. In the absence of the wreckage the precise reason for the fuel loss cannot be determined. Calculations relating to aircraft performance revealed that had the pilot elected to remain at the planned cruising level, the aircraft could have glided for about 35 nm after fuel expiry, with both propellers feathered. It was considered that had the pilot elected to turn back when he realised the nature of the problem and maintained altitude until the remaining fuel was exhausted, the aircraft could have reached the northern Tasmanian coast. There is no known hazard associated with a potential loss of cabin pressurisation that would have required an emergency descent from FL 120. The pilot's reason for conducting such a descent could not be established, however the effect of the decision was that the aircraft was ditched at an earlier time, and further from the Victorian coast, than was necessary. This factor increased the difficulties encountered during the subsequent search and rescue operation."