THE family and friends of six people killed in a plane crash on the Sunshine Coast hinterland may finally learn the truth a year after their deaths.
The Australian Transport and Safety Bureau's final report is expected to be released at the start of next month, detailing why the vintage 1934 de Havilland DH84 Dragon bi-plane crashed on October 1 last year.
Pilot Des Porter, 69, his wife, Kath Porter, 61, John and Carol Dawson, both 63, and Les and Jan Devlin, 75 and 61, were all killed in the crash 36km south-west of Gympie.
A preliminary investigation detailing the flight history, weather forecast, witness reports and aircraft information was released in November last year.
The report found the aircraft had departed a vintage aircraft show in Monto, with six persons on board, after organisers were forced to bring the event to an early close due to bad weather.
The pilot, Mr Porter, later reported entering thick cloud and requested assistance from air traffic control to help him exit the conditions.
After a while, communication with the aircraft was lost.
It took two days for more than a dozen helicopters to find the wreckage.
It was believed Mr Porter - who survived a plane crash that killed his father and brother as a boy - crashed after becoming disoriented in the cloud.
A four-member ATSB team of investigators worked alongside police sifting through the crash scene at upper Kandanga for several days, describing the wreckage as "not in a condition that you would recognise as a plane".
They said only the plane's two engines and propellers, as well as a number of aircraft instruments, were found intact.
Several electrical and communication devices - some believed to be mobile phones taken on board by the passengers - were also examined.
The plane's GPS circuit board was recovered, but at the time the investigators feared the impact had damaged the board and the data could have been affected.
The final report is expected to detail the final moments before the plane crashed.