Loss of separation involving a Piper PA-23-250, VH-MBU and Boeing 737-376, VH-TAK, Cairns Aerodrome, Queensland, on 27 August 1996

FACTUAL INFORMATION

A Piper PA23 aircraft, VH-MBU, on a right base leg for runway 15 conflicted with a Boeing 737 on left base leg as a result of a co-ordination breakdown.

VH-MBU was inbound from Stoney Creek and the Approach 2 controller co-ordinated with the Tower Controller to process the aircraft via right base leg behind a Boeing 747 on final approach for runway 15. The pilot was asked to sight the B747, which he did. The pilot was then told to contact the Tower. There was no co-ordination with Approach 1. The Approach 1 controller had transferred a Boeing 737 VH-TAK, to the Tower and asked Approach 2 what he was doing with MBU and should TAK be following MBU, to which he replied in the affirmative. TAK was turning left base on Tower frequency by this time. Co-ordination with the Tower Controller alerted him to the confliction. The Tower Controller advised MBU to orbit right base and TAK was allowed to continue with the visual approach.

Radar data confirmed that the two aircraft conflicted with a separation of 1.5 NM at the closest point of approach.

ANALYSIS

The Approach 2 controller failed to co-ordinate the landing sequence with the Approach 1 controller. The reason for this lapse in performance was not positively established but the controller's supervisor thought that a desire to provide an expeditious service may have been a contributing factor.