An ATSB preliminary report outlines the sequence of events prior to a mid-air collision between a Cessna and a Jabiru light aircraft near The Oaks, south-west of Sydney on 26 October.
The two pilots in the Cessna 182, a pilot under examination for their Commercial Pilot Licence (CPL) and an approved flight test examiner, and the single pilot in the Jabiru were fatally injured in the accident, which occurred in non-controlled airspace.
"The ATSB has been able to build a comprehensive understanding of the accident's sequence of events thanks to a range of recorded and transmitted data sources, including an on-board video camera in the Jabiru, electronic flight bag data, air traffic control surveillance data, and CCTV footage, as well as interviews with witnesses," said ATSB Chief Commissioner Angus Mitchell.
The report details that the Jabiru was one of three aircraft that had planned to fly from The Oaks to Cessnock as a social activity. The first aircraft in that group, another Jabiru, had departed about 30 seconds ahead of the accident aircraft, while a third, faster aircraft was planned to depart 10 minutes later.
However, a few minutes after taking off to the south and then turning to the north to fly towards Cessnock, the lead Jabiru pilot radioed that they had decided to turn back to The Oaks due to experiencing turbulence. The pilot of the accident Jabiru then also decided to return to The Oaks, turning back ahead of the first Jabiru to make an approach to The Oaks' runway 18.
Meanwhile, the Cessna 182 had been conducting circuits at Camden, as part of the CPL flight test, having originally departed Shellharbour. After a final touch-and-go, the Cessna climbed to an altitude of about 1,300 ft and tracked to the south-west before making a left turn to track south-south-west and beginning to climb.
Separately, on its return to The Oaks, the Jabiru had conducted a go-around, flying along the runway at about 100 ft before climbing and making a right turn to conduct a circuit.
"The mid-air collision occurred when the Jabiru was flying to the north on the downwind leg of the circuit for The Oaks ahead of a planned landing, and as the Cessna was tracking to the south-south-west," Mr Mitchell explained.
Both aircraft were on near reciprocal headings and on relatively constant flight path trajectories at the time of the collision, with the video showing the Jabiru in straight and level flight and the Cessna climbing, with no avoiding action evident by either aircraft.
"We know from witnesses accounts and the on-board video that the Jabiru pilot was making radio calls on the frequency for The Oaks, and as the investigation progresses we will continue our analysis of video recordings and radio transmissions to better understand what awareness the pilots in both aircraft had of the other aircraft," Mr Mitchell said.
"We will also continue to further review the radio and communication, electronic conspicuity and surveillance equipment fitted to both aircraft, procedures for non-controlled aerodromes, and operator documentation."
Mr Mitchell stressed that the preliminary report only details factual information established in the investigation's early evidence collection phase and does not contain analysis or findings, which will be detailed in the investigation's final report.
"While this preliminary report contains no findings, the ATSB does continue to strongly encourage the fitment of ADS-B transmitting, receiving and display devices in all aircraft, as they significantly assist the identification and avoidance of conflicting traffic," he said.
"In addition, the ATSB publication A pilot's guide to staying safe in the vicinity of non-towered aerodromes highlights some of the known challenges presented to pilots operating around airfields in non-controlled airspace."
