The crew of a Boeing 737 (B737) received a traffic alerting and collision avoidance system (TCAS) resolution advisory to reduce climb when passing 800-1,000ft on departure from runway 34R at Sydney. This was immediately followed by a TCAS instruction to descend. As the crew commenced descent, the clear of conflict command was heard and a Kawasaki BK 117 helicopter sighted passing to the left in the opposite direction at a distance of about 1 NM.
The investigator reviewed radar data and air traffic control automatic voice recordings to establish the sequence of events. The investigation found that the aerodrome controller East was controlling the B737 and the helicopter was being controlled by the aerodrome controller West. Through a comprehensive coordination process, both controllers were aware of the other controller's traffic.
The helicopter was inbound from the north on a Medical Category 2 flight to Prince Henry Hospital and was cleared by the West controller to track via the runway intersection at 2,000 ft. The West controller had provided this advice to the East controller, who agreed with the clearance and advised that the helicopter was not required on his frequency.
Prior to clearing the B737 for take-off, the East controller alerted the West controller of his intention to launch the B737. The West controller advised that he would keep the helicopter to the west of the B737. The B737 was departing from runway 34 R and was cleared via an ENTRA TWO standard instrument departure (SID). The SID required a right turn after departure to intercept the Sydney 023 VOR radial. Because the aircraft had been cleared for take-off and was on an unrestricted climb, there was the potential for conflict with the helicopter, which was inbound to Sydney from the north at 2000 ft.
Approximately 30 seconds after the B737 had been cleared for take-off, the West controller asked the helicopter pilot to report sighting a 737 on departure roll on runway 34R. The pilot reported sighting the B737. The West controller then advised the helicopter pilot of the B737's intentions and assigned the pilot the responsibility for separation. The pilot acknowledged this.
The TCAS on the B737 activated with a resolution advisory some 20 seconds later and the two aircraft passed each other with 0.9 NM horizontal and 500 ft vertical separation.
Visual separation of air traffic was a valid method to use in these circumstances. However, the criteria for its application were clearly detailed in the Manual of Air Traffic Services (MATS) Part 4 Section 5. In particular, MATS 4.5.1.10 stated: "In circumstances where an aircraft has been instructed to maintain separation from, but not follow, an IFR aircraft, traffic information shall be issued to the IFR aircraft, including advice that responsibility for separation has been assigned to the other aircraft". The B737 was an IFR aircraft but was not provided with the required traffic information.