Loss of separation involving a Beech Aircraft Corp B200C, VH-AMS and British Aerospace PLC 3107, VH-TQK, Port Macquarie, New South Wales, on 15 March 1993

Circumstances

At 1635 hours VH-TQK departed Port Macquarie for Sydney via a track of 221 deg from Port Macquarie. An airways clearance was issued by RAAF Williamtown Air Traffic Control [ATC] for VH-TQK to enter controlled airspace [CTA] on this track on climb to Flight Level [FL] 160.

At 1537 hours VH-AMS departed Port Macquarie for Williamtown on a track of 200 deg from Port Macquarie. An airways clearance was issued by Williamtown ATC for VH-AMS to enter CTA on this track to FL 140.

The clearances were issued when neither aircraft was identified on radar and with no vertical or longitudinal separation requirement. In such circumstances the only separation standard available is lateral which required 30 deg between the departure tracks in question. As only 21 deg existed, a breakdown in separation occurred.

Radar analysis indicates that the aircraft were 7.6 NM apart when they were established in CTA and that this distance increased before radar identification was complete. It also shows that the vertical difference was a minimum of 500 ft which occurred prior to identification.

Significant Factors

1. The Williamtown air traffic controller issued procedural airways clearances that were not in accordance with the appropriate separation standard.