In mid-October 2023, a Sling light sport aircraft and a Piper Cherokee operating in the Moorabbin training area, south-east of Melbourne came within 100 metres of each other while both aircraft were flying at the same altitude.

The crew of the Sling reported to the ATSB they observed seeing the Cherokee pass in front of their aircraft in close proximity. ADS-B data obtained by the ATSB confirmed the Sling crew’s report, as well as showing just how close both aircraft came to colliding mid-air.

Neither aircraft were equipped with ADS-B IN systems, and nor were they required to be. An ADS-B IN capability with a cockpit display or an electronic flight bag application showing traffic information can significantly enhance the situational awareness for a pilot, particularly when flying in non-controlled airspace.

“The ‘see and avoid’ principle for pilots has known limitations, and the use of ADS-B IN with a cockpit display or an electronic flight bag application showing traffic information greatly improves a pilot’s situational awareness and enhances the safety of their flight,” ATSB Chief Commissioner Angus Mitchell said.

“When flying in non-controlled airspace it’s important to have a high level of situational awareness, and one tool that can help you and other pilots is ADS-B IN.”

To support its investigation into the mid-air collision of two IFR training aircraft near Mangalore Airport in February 2020, the ATSB initiated an aircraft performance and cockpit visibility study to determine when each aircraft may have been visible to the pilots of the other aircraft*. The study clearly showed that had the aircraft been equipped with ADS-B IN, the pilots would have been assisted in locating the other aircraft and alerted to its position much earlier than by visual acquisition.

In lieu of a formal transport safety investigation into the Moorabbin training area near-collision, the ATSB is using this occurrence to further encourage all eligible general and recreational aircraft owners and pilots to equip their aircraft with ADS-B OUT, and to strongly consider using ADS-B IN for enhanced situational awareness.

To incentivise voluntary uptake of ADS-B installations in Australian–registered aircraft operating under Visual Flight Rules (VFR), the government is providing a 50 per cent rebate on the purchase cost – capped to $5,000 – of eligible devices and, where applicable, the installation. While eligibility rests on equipment providing an ADS-B OUT capability, devices that provide ADS-B IN, as well as low-cost portable ADS-B devices, are also eligible for the grant.

If you have not already, and you are eligible, please take advantage of the generous rebate to equip your aircraft with ADS-B before the offer ends on 31 May 2024.

More information, including on how to apply for the rebate is available at:

The image used in this news story is a still extracted from an animation created as part of the aircraft performance and cockpit visibility study.

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