On 21 June 2013, a Fairchild SA227 aircraft, registered VH‑HVH (HVH), was being operated on a scheduled passenger flight from Bathurst Island to Darwin, Northern Territory. The crew broadcast a taxi, entering the runway, and a rolling call on the Bathurst Island common traffic advisory frequency (CTAF). After take-off, the crew broadcast another call advising that they intended to depart the circuit on the downwind leg, on climb to 5,000 ft.
At about the same time, the pilot of an Aerospatiale AS.350 helicopter, registered VH‑JRJ (JRJ), was taxiing at Barra Base, near the Port Hurd aeroplane landing area (ALA) for a ferry flight to Darwin. The pilot reported broadcasting a taxi and an airborne call on the CTAF. He had planned to overfly the Bathurst Island aerodrome, along the coast to Cape Gambier and then to Darwin.
When at 16 NM and 7 NM from the Bathurst Island aerodrome, the pilot of JRJ broadcast a call on the CTAF advising he was overflying the aerodrome and then flying coastal to Cape Gambier at 2,500 ft.
At 1709, HVH was on downwind, climbing through 2,000 ft when the first officer sighted a helicopter (JRJ). The captain had been recording the departure time and looked up and saw JRJ about 50-100 ft above and 400 m to his right. The first officer initiated a descent and JRJ passed overhead.
The crew of each aircraft had not heard the other on the CTAF.
The captain of HVH suggested that enhanced VHF coverage would improve communications, enabling pilots to hear broadcasts made both on the ground and airborne over a larger area.
This incident emphasises the importance of alerted see-and-avoid practices and the importance of safety when operating around non-towered aerodromes.