Bad weather probably caused the pilot of a Piper PA-28 aircraft to become disoriented before it crashed off the Victorian coast near Barwon heads, a report from the Australian Transport Safety (ATSB) says.
On January 29, 2016, the plane left Melbourne's Moorabbin Airport just after midday on a private flight for King Island, Tasmania.
The plane passed over Point Lonsdale and encountered low visibility, so the pilot turned the plane around to head back towards land.
Two minutes later, the aircraft turned right and made a rapid descent, crashing into the water at 12:27pm, 6.6 kilometres south-west of Point Lonsdale.
All four people onboard, Ian Chamberlain, Daniel Flinn, Donald Hately and Dianne Bradley, died.
Witnesses said the aircraft was in a nose down position as it hit the water and the engine sounded as though it was producing power.
The Australian Transport Safety Bureau (ATSB) report into the crash found the pilot's decision to keep flying towards an area of low cloud and rain was "likely influenced by the inherent challenges of assessing low visibility conditions".
It also found the pilot "likely experienced a loss of visual cues and became spatially disorientated, leading to a loss of control and impact with the water".
Decision to fly
Two of the plane's passengers arrived at Moorabbin Airport at 8:00am on the day of the flight and decided the weather around the airport was not suitable to fly in.
They used the National Aeronautical Information Processing System to access aerodrome forecasts and weather observations, and also called the Bureau of Meteorology.
The ATSB report showed one of the passengers believed the weather was slowly moving east and that it was clearing to the west.
At about 10:00am the pair at the airport contacted the other passenger and it was reported the decision was made during that exchange.
The report found their understanding that the weather was improving at Moorabbin Airport and "the successful departure/arrival of other aircraft at the airport, contributed to their decision to depart".
Weather during flight
The ATSB's analysis of the forecasts relevant to the flight identified a complex weather system with rain, low cloud and isolated thunderstorms over the sea and coast on the day.
Three other planes made the same flight to King Island.
One returned to Moorabbin, two other pilots continued on to King Island and all three report reduced visibility conditions in the area.
Witnesses fishing in the vicinity of Point Lonsdale reported hearing an aircraft pass nearby at what they interpreted to be a "very low altitude".
Due to the low cloud and visibility in the area they could not initially see the aircraft.
Editor's note: This story has been updated as the ATSB report did not identify the pilot.
