A student pilot taxied onto a runway at a Queensland airfield prompting an incoming plane to abort the landing, leading to a fatal crash, an investigation has found.
Former commercial pilot David Maddern and his wife Jan, both in their 60s, were killed in July as their Jabiru J430 took off from Caboolture aerodrome and collided midair with a Piper Pawnee glider tug aircraft.
The Piper had been coming into land, but its pilot had instigated a go-around after a third plane, a Cessna 172, had taxied onto the runway.
In its preliminary findings on Friday, the Australian Transport Safety Bureau (ATSB) said the student pilot had reported turning down the aircraft's radio volume to conduct engine run-ups and had not subsequently restored normal volume.
It said as a result, the pilot did not hear any transmissions from the Piper aircraft and was not aware of it approaching runway 06.
As the Piper approached, the Cessna taxied across the runway forcing the go-around. It was as it began climbing that the Jabiru took off from an intersecting runway.
About five to 10 seconds later, while both aircraft were climbing on crossing tracks, the pilot of the Jabiru made a left turn, likely in an attempt to avoid a collision, the ATSB said.
The two aircraft collided above runway 06 and while the Piper was able to land, the Jabiru crashed, with both occupants killed.
ATSB chief commissioner Angus Mitchell said using CCTV footage, some recorded radio calls, witness accounts, and an examination of the accident site, investigators had been able to build an understanding of the tragic accident’s sequence of events.
"However, I would caution against making any assumptions as to the contributing factors to this accident, and I would note that aviation systems have multiple layers of defence in place to prevent accidents,” he said.
“Not all radio calls at Caboolture were recorded and our analysis of witnesses recollections of radio calls is continuing, so we are still building our understanding of the nature of the calls made, and giving consideration to a range of other potential factors.”
Mr Mitchell said investigators would continue to analyse aircraft flight paths, paying particular attention to potential visibility restrictions.
They would also review aircraft, pilot, airfield and operator documentation, analyse procedures at non-controlled aerodromes with intersecting runways, and further examine aircraft components and other items recovered from the accident site, including two data recording devices from the Jabiru.
A final report into the crash will be released at a later date.
