Loss of separation involving a Boeing 767-338ER, VH-OGO and Robinson R22 Beta, VH-HSC, 5 km south of Cairns, Queensland, on 27 September 1994

Sequence of Events

The crew of VH-OGO, when established on final approach to runway 33, reported a TCAS RA (Resolution Advisory) against an unknown aircraft indicating half a nautical mile west at the same level, 1,000 ft AMSL. The other aircraft, VH-HSC, a helicopter, was tracking west of the Cook Highway to the south-eastern training area. A breakdown in separation had occurred.

The pilot of the helicopter had been given a clearance by SMC (Surface Movement Control) to track to the western training area via Green Hill. The ADC (Aerodrome Controller) later amended this clearance for the aircraft to remain west of the Cook and Bruce Highways. The departure of the helicopter was not monitored by the ADC due to distractions in the Control Tower. The ADC expected the helicopter pilot to track directly to the south-western section of the Bruce Highway which is due south of the aerodrome. The pilot instead tracked west of the Cook Highway which closely parallels the final approach path to runway 33.

Analysis

When the two aircraft passed each other, the helicopter which had not reached the junction of the two highways was still being operated within its clearance restriction of "west of the Cook Highway", although this was not what the ADC intended. The ADC failed to monitor the helicopter's departure thus did not ensure adequate separation of the outbound helicopter and the inbound passenger jet.

Safety Action

As a result of this incident, a caution has been inserted in the Air Traffic Services Local Instructions stating that at a departure clearance west of the Cook Highway does not provide separation with final runway 33.