On 23 January 2012, the pilot of a Robinson Helicopter Company R44 Raven II helicopter, registered VH-HYC (HYC), was conducting a routine gas pipeline inspection flight between Parramatta and Castle Hill, New South Wales.
When 1 NM (1.85 km) north of Parramatta, the pilot of HYC observed a Piper Aircraft Corporation PA-28-161, registered VH-TAK (TAK), tracking northbound from Bankstown, pass overhead, about 20 ft above. In response, the pilot of HYC immediately lowered the collective and commenced a descending right turn.
A review of Airservices Australia radar surveillance data indicated that the distance between HYC and TAK reduced to 0.2 NM (370 m) laterally, with both aircraft at the same altitude of 1,400 ft. The aircraft were operating in uncontrolled airspace and were not subject to air traffic control services.
This incident highlights the advantages of utilising two communication systems, if fitted, to enhance traffic awareness. It further emphasises the benefits of notifying the appropriate air traffic control authority if intending to conduct aerial work within a known area of high traffic levels, such as the Bankstown lane of entry.