THE pain of losing six people in an horrific plane crash in the Sunshine Coast hinterland will never ease for their family and friends.
But today, loved ones may at least feel a sense of closure when the Australian Transport and Safety Bureau releases its final report into why a vintage 1934 de Havilland DH84 Dragon bi-plane crashed into a steep, densely wooded ridge about 15km west of Imbil.
Pilot Des Porter, his wife Kath and their long-time friends Les and Janice D'evlin and John and Carol Dawson were killed when the plane went down on October 1 last year.
The plane was returning to Caboolture after the group raised money for charity by giving joy flights at the Monto Fly-In aircraft show.
Rescuers searched for two days in difficult conditions for the wreckage.
"Over the next 50 minutes ATC provided assistance to the pilot and a search and rescue (SAR) helicopter was dispatched to the area.
"From the pilot's radio calls it was apparent that he was unable to navigate clear of the cloud.
"Radio contact was intermittent and no transmissions from the aircraft were received after 1405.
"An extensive search was initiated, and the aircraft wreckage was located on 3 October in high terrain.
"The aircraft was destroyed and there were no survivors.''
What the ATSB found
With no or limited visual references available in and near cloud, it would have been very difficult for the pilot to maintain control of the aircraft.
After maintaining control in such conditions for about an hour, and being unable to navigate away from the mountain range, the pilot most likely became spatially disoriented and lost control of the aircraft before it impacted the ground.
Due to the limited radio and radar coverage in the area, the ability of ATC and the SAR helicopter to assist was limited.
However, the ATSB found that there were areas of potential improvement in the management of in-flight emergencies and coordination between ATC and SAR aircraft.
What's been done as a result
Airservices Australia and the Australian Maritime Safety Authority agreed to conduct a comprehensive review of their existing memorandum of understanding to ensure the effectiveness of collaborative in-flight emergency responses.
The review is anticipated to be completed by the first quarter of 2014.
Though it remains unclear precisely how the aircraft came to be in instrument conditions, this accident highlights the importance of pre- and in-flight planning and decision-making in limiting exposure to risk.
It is important for pilots to incorporate approved weather forecasts, knowledge of the terrain, and diversion options into their flight planning, to plan for contingencies prior to and throughout a flight, and to carry out those plans well before encountering difficulty.
A preliminary investigation detailing the flight history, weather forecast, witness reports and aircraft information was released in November last year.
That report indicated weather and dense cloud coverage had played a factor in the crash.
It said there were no indications of an aircraft malfunction.
Crash worst in history of Caboolture club
Caboolture Aero Dynamic Flight Academy managing director Bryan Carpenter, a close friend of Mr Porter, said the crash had been the worst in the history of the Caboolture airfield.
He said the report should give everyone the firm answers they were looking for.
"I know this will bring some closure for the family," he said.
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