Aviation groups and the family and friends of the two pilots killed in a mid-air collision near Gympie fear they may never know what went wrong because the Australian Transport Safety Bureau (ATSB) is refusing to investigate the crash.
Experienced pilots Christopher "Bob" Turner, 80, of Caboolture, and Barry Irvine, 77, of Glenwood, died on November 9.
Mr Turner was flying a glider and Mr Irvine was behind the controls of a small recreational plane.
The aircraft collided in the clear sky above a dairy farm at Kybong, a few kilometres away from the Gympie aerodrome.
Gliding Australia president Steve Pegler said the ATSB should "absolutely" be investigating.
"There's all these safety lessons that are still to be learned out of it," Mr Pegler said.
"We've got two people who have died and the ATSB has walked away from it … which is a real shame — it's a lost opportunity."
Recreational Aviation Australia (RAAus) has echoed the call.
Chief executive Matt Bouttell said the Transport Safety Investigation Act provided an "out" for the ATSB, because the accident involved sport aircraft.
"They've chosen not to … however, ultimately an independent review needs to be done," he said.
"This is about two aircraft in a very busy airspace, not far from a major airport … where this may have been two large, passenger-carrying aircraft."
The Queensland Police Service's Forensic Crash Unit is investigating, but a spokesperson said no comment could be made while the case was open.
Mr Pegler said he respected the police's efforts.
"But they're not subject matter experts when it comes to aviation," he said.
"We'd be quite happy to offer that assistance if they asked for that, but they haven't at this stage."
Tragedy strikes twice
The lack of an investigation by the national authority has been a bitter blow for Mr Irvine's family.
Mr Irvine's brother Colin died in a hang-gliding accident in 1975.
Surviving brother Terry Irvine said Colin's accident was thoroughly investigated by the Civil Aviation Safety Authority at the time.
"There was no definite conclusion on the cause and that left us maybe with some questions unanswered, but at least there was an attempt to find answers," Mr Irvine said.
He said while he supported the police investigation into Barry's accident, he feared it would not lead to changes that could prevent similar tragedies.
"I have problems going back to sleep because there are questions churning over in my mind," Mr Irvine said.
"The hard part is ... knowing that we will probably never find the answers in this situation.
"I don't want to be calling for any bans on recreational or light aircraft activities … but at least some sort of investigation … in the hope that the number of accidents is reduced, to stop other families from going through what my family and the other pilot's family are going through."
Caboolture Gliding Club president Garrett Russell flew with Mr Turner for years.
"He was one of the most experienced and most meticulous pilots that I had the pleasure of flying with, and a great instructor," Mr Russell said.
"People have died … an investigation would be very valuable for all pilots … to know what happened, because a mid-air collision is something that can happen to any aircraft.
"It's rare … but we want to make it even more rare."
No new 'learnings'
ATSB chief commissioner Angus Mitchell said it was a "long-established government policy" to prioritise resources on investigations with the potential to deliver the greatest public benefit.
Mr Mitchell said mid-air collisions were rare and any ATSB investigation would be "unlikely to yield new safety learnings for the aviation industry".
He said there was "self-administration arrangements" for the recreational sector to undertake its own accident investigations.
"Where requested and as resourcing permits the ATSB may assist sport and recreation aviation organisations," Mr Mitchell said.
"The ATSB empathises with the next of kin who have lost loved ones in the Kybong accident and are seeking answers as to how the accident occurred."
Mr Bouttell said his group had conducted investigations in the past, but it should not have to.
"Enough is enough on the basis that we expose our people, our own employees and volunteers, to some pretty horrific scenes," he said.
"Furthermore, the expertise lies with our ATSB."
