Loss of separation involving a de Havilland Canada DHC-8-102, VH-TNG and Beech Aircraft Corp D95A, VH-CFQ, Brisbane, Queensland, on 8 September 1993

Aircraft under the control of Brisbane Approach (North) in the period leading up to the occurrence included:

- VH-TNG which was on left downwind at 3000 feet for a runway 01 ILS approach.

- VH-CZL which was about 20 nm final for runway 01 ILS approach.

- VH-JEX, a VFR aircraft out of Brisbane, heading north-west on climb to 4500 feet.

- An Army helicopter transiting Approach (North) airspace south of the aerodrome.

- A number of aircraft inbound from the north-west.

As VH-JEX climbed, it experienced problems maintaining visual flight and required a number of clearance amendments with respect to both heading and altitude. During this process, the Approach (North) controller became aware of another aircraft, VH-CFQ orbiting Archerfield at 1000 feet awaiting clearance into Approach (North) airspace. The controller involved said that he was not sure how long VH-CFQ had been airborne at Archerfield but was aware of feeling under some pressure to issue a clearance.

He cleared VH-CFQ to enter controlled airspace on climb to 3000 feet west of the Mt Coot-tha TV towers and returned his attention to VH-JEX and the inbound traffic from the north. A short time later, he looked to check the progress of VH-CFQ and saw a conflict with VH-TNG developing. He instructed both aircraft to turn left. However, this resulted in VH-TNG conflicting with VH-CZL. The controller then told VH-TNG to turn right for separation with VH-CZL. The 5 nm separation standard was infringed in both instances, the radar recording indicating the minimum distance to have been 3.5 nm each time.

SIGIFICANT FACTORS

1. Controller workload was significantly increased by the clearance amendments necessary for VH-JEX.

2. The controller felt under pressure to clear VH-CFQ from Archerfield into controlled airspace.

3. The clearance given to VH-JEX was inappropriate and led to the losses of separation.