A pilot with a history of dangerous landings ignored a snow storm warning shortly before he flew into a mountain, killing himself and two passengers, investigators have found.
The Piper Navajo Chieftain came down in overcast, snowy weather on final approach to Mount Hotham, in Victoria's alpine region, on July 8 last year.
Gold Coast property developer Brian Ray, his wife Kathy and pilot Russell Lee died in the crash.
The wreckage and the bodies were found three days later in weather conditions that forced rescuers to search on foot and horseback through heavy snow.
The Australian Transport Safety Bureau's final report into the air crash, released today, found a phenomenon known as flat light also contributed to the crash.
Flat light, which occurs typically when the weather is overcast, can affect a pilot's perception of depth, distance, altitude and topographical features.
It affects depth perception and can make it impossible to distinguish features on a snowy slope.
Mr Lee had considered diverting to Wangaratta but chose to land at Mount Hotham airport despite advice from a weather observer there that the aircraft would not be able to land, the report found.
The pilot had switched from a visual to an instrument landing, but the report found conditions were not suitable for landing using either method.
Two earlier flights had diverted to other airports because of the poor conditions.
Sleet and snow showers, visibility to 300 metres, and an unbroken cloud base between 30 and 60 metres above the ground greeted the aircraft at the time of the crash, the report said.
"The weather conditions were ideal for a flat light phenomenon that was likely to have denied the pilot adequate visual reference," the report said.
"The pilot may have experienced disorientation and loss of situational awareness.
"Staff at Mount Hotham and pilots interviewed by ATSB reported that they had observed the pilot land at Mount Hotham in weather conditions unsuitable for aircraft arrivals," the report said.
"The pilot was known, by his chief pilot and others, to adopt non-standard approach procedures to establish his aircraft clear of cloud when adverse weather conditions existed at Mount Hotham.
"This accident highlights the unsafe nature of such practices.
"The investigation was unable to determine why the pilot persisted with his attempt to land at Mount Hotham in such adverse weather conditions.
"However, it is possible that over-confidence and commercial or family pressures influenced the pilot's decision making."
ATSB has recommended the Civil Aviation Safety Authority review its surveillance methods, which may include cooperation with Airservices Australia, to detect patterns of unsafe flying practices and non-compliance with regulatory requirements.