The collision, which killed four people, involved a Piper Seminole and a Beech Travel Air aircraft.
The report details basic facts established in the investigation’s early evidence collection phase.
It also outlines the collision’s sequence of events using several sources including ADS-B transponder data and information from an iPad with an electronic flight bag app installed.
The report also outlines weather information at the time and notes there was no recording of the Common Traffic Advisory Frequency (CTAF).
The Travel Air aircraft departed Tyabb Airport for a return Instrument Flight Rules (IFR) training flight to Shepparton via Mangalore with an instructor and student pilot on board at 10.55 am.
Meanwhile, the Seminole advised Air Traffic Control (ATC) at 11.11 am that it was taxiing for departure from Mangalore for a round-trip IFR flight via Essendon and Shepparton. An authorising testing officer and pilot were on board.
Six minutes later, the Travel Air began its descent from 6000 ft for airwork at Mangalore between 4000 ft and ground level.
ATC advised the Travel Air of the departing Seminole from Mangalore. The Seminole then made a departure call, advising ATC of a planned climb to 7000 ft. ATC passed details of the Travel Air’s intended airwork to the Seminole.
The two aircraft collided at 11.24 am about 8 km south of Mangalore Airport at an altitude of about 4100 ft.
The Seminole travelled for about half a kilometre to the east before crashing in an open field, while the Travel Air continued north and impacted a lightly wooded area 1.4 km from the collision point.
Debris was found in an area ranging from 1.6 km to the north-north-east and about 200 m to the west of the Hume Hwy.
Examination of the recovered radios, weather conditions at the time of the accident, recorded area frequency calls and recollections of CTAF radio broadcasts will be the focus as the investigation moves forward.
Other areas for investigation include air traffic services actions, procedures and practices, traffic density in and around Mangalore Airport and classification of its airspace and visibility from both aircraft.
ATSB Chief Commissioner Greg Hood noted preliminary reports did not contain findings, identify contributing factors or outline safety issues and actions, which will be detailed in an investigation’s final and any interim reports.
“Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties so appropriate safety action can be taken,” Mr Hood said.
A final report is expected to be completed next year.
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