Background
On the morning of 2 July 1978, a pilot obtained meteorological forecasts and filed a VFR flight plan from Moorabbin to Flinders Island and return. The pilot did not hold an instrument rating, restricting the flight to Visual Flight Rules. Forecasts indicated patches of fog initially, with rain later, and broken layers of stratus and strato-cumulus cloud, but nothing suggested VFR flight would be impossible. The flight plan estimated 89 minutes to Flinders Island and 72 minutes return, with a fuel endurance of 300 minutes.
Flight Details
The aircraft departed Moorabbin at 1007 hours after being refueled to capacity. The pilot reported in the Flinders Island circuit area at 1143 hours and landed. The pilot and a passenger proceeded by motor vehicle to a farming property about 40 km away. Later, upon returning to the aerodrome, the pilot attempted to obtain updated weather information but found the telephone unserviceable. Forecasts had been amended to indicate some deterioration, particularly increased low cloud, but still suggested VFR flight was possible.
The pilot and passenger boarded the aircraft, which took off and circled before being obscured by cloud. At that time, weather south of Flinders Island was squally, and the nearby mountain was partly cloud-covered. At 1543 hours, the pilot contacted Launceston Flight Service Unit (FSU), reporting departure at 1541, intention to cruise below 5000 feet, and estimated time over South East Point (southern Wilson's Promontory) at 1617 hours. He asked if Moorabbin was open to VFR traffic and was advised it was not closed but expected to be. He was given the terminal forecast for Moorabbin and area forecasts regarding cloud.
At 1551 hours, the pilot contacted Melbourne FSU. At 1600 hours, he again asked if Moorabbin was open to VFR and was told yes. He reported climbing to 6500 feet, then at 1607 hours to 8500 feet. At 1620 hours, he amended his estimated time over South East Point to 1625 hours and again requested confirmation that Moorabbin was still open, which was affirmed. At 1622 hours, a rapid broadcast of the call sign was heard with raised pitch; the flight service officer did not understand and requested a repeat. No reply followed, and no further communications were received.
Search and Recovery
After the aircraft failed to report over South East Point, the Uncertainty Phase was declared at 1640 hours. After widespread checks, the Alert Phase was declared at 1713 hours, upgraded to Distress Phase at 1745 hours. An air, land, and sea search continued for three days. On 3 July 1978, two seats and a left main wheel assembly from a Partenavia P68B were found on the eastern shoreline of Wilson's Promontory. Three life jackets with the name 'TIPPETT' stencilled on them were also found in the same area. No trace of the main wreckage or occupants has been found. Damage to the recovered items was consistent with high-speed impact with water in a nose-down, left wing-down attitude.
Weather Analysis
Post-accident meteorological analysis indicated a complex low-pressure system moving across Victoria. Extensive cloud cover existed over Wilson's Promontory, with a cloud base of 1000 to 2000 feet. Visibility was reduced in areas of heavy rain showers. The interaction of differing air masses could have produced conditions conducive to severe airframe icing for aircraft operating between 5000 and 7000 feet.
Probable Cause
There is insufficient evidence available to enable the cause of this accident to be determined.