On the afternoon of 13 March 2003, the pilot of a Eurocopter AS350-B2 helicopter, registered VH-PHB, was conducting a police surveillance operation to the north and west of Bankstown, NSW at 4,000 ft. The pilot was operating on the Departures West radio frequency. The area of operation for the helicopter was not clearly defined and a clearance limit had not been applied. The Departures West controller had passed radar identification details of the helicopter to the Departures South controller as the helicopter was operating in that controller's area of responsibility. The Departures South controller was required to ensure that any aircraft under their jurisdiction was separated from the observed radar track of the helicopter. However, the helicopter was maintained on the Departures West radio frequency. The Departures West control position was subsequently subject to a handover/takeover to a new controller.
A short time later, a Saab 340B (Saab), registered VH-KDQ, departed Sydney Airport's runway 34 left (34L) at about 1805 Eastern Summer Time on climb to 3,000 ft into the Departures South controller's area of responsibility. The Saab was followed, with minimum radar separation, by a de Havilland DHC-8-314 (Dash 8), registered VH-TQA. The Departures South controller was concerned that the Dash 8 was faster than the Saab and consequently cleared the Saab crew to climb to 5,000 ft at about 1807. About one minute later, a short-term conflict alert (STCA) activated on the TAAATS system and a breakdown in separation occurred between the Saab and the helicopter.
The pilot of the helicopter was immediately instructed to turn left and was given traffic information about the Saab by the Departures West controller. After the pilot reported seeing the Saab, he was instructed to maintain visual separation from it. The Departures South controller, who also received the STCA, instructed the crew of the Saab to turn left onto a southerly heading to move it away from the helicopter's position. Recorded radar data indicated that the minimum separation between the helicopter and the Saab was 2.15 NM laterally and 700 ft vertically.
The investigation found that the Departures South controller had been operating in that control position for 15-20 minutes before the occurrence. As the Departures West controller had only recently assumed responsibility for that position, it is possible that neither controller realised the extent of the area of operation of the helicopter. The Departures South controller was also distracted by the close proximity between the departing Saab and Dash 8.
The occurrence aircraft, although operating in the same volume of airspace, were operating on different control frequencies. The controllers did not clearly enunciate which of them was responsible for separation of the occurrence aircraft. As the area of operation for the helicopter was not clearly defined, it was difficult for the controllers to apply separation assurance.