Loss of separation involving a Airbus A330-300, 9MMKH and Airbus A320-211, VH-HYJ, 172km NW Brisbane, Aerodrome, QLD on 25 May 1997

The controller involved was undergoing a check. MAS135 and VH-HYJ were third and fourth in a six aircraft sequence. Both aircraft were inbound to Brisbane from the north-west with VH-HYJ behind MAS135, and operating at a higher speed. As the sequence progressed, the controller was late in detecting the reducing separation between the two aircraft. VH-HYJ was turned away from MAS135 but not sufficiently early to prevent lateral separation reducing to 4NM. At this time, vertical separation was 500 feet.