Breakdown of co-ordination involving a Boeing 737-376, VH-TAH and McDonnell Douglas F/A-18A, near Williamtown, New South Wales, on 2 December 1992

Circumstances

RAAF Williamtown were operating FA18 aircraft in Restricted Areas R457 and R527. In order to return these aircraft to Williamtown at the completion of their task, it was necessary to transit civil controlled airspace under the control of Sydney Sectors 1, 2 and Arrivals.

Williamtown air traffic control [ATC] co-ordinated with Sydney Sector 1 for the recovery of two FA18 aircraft and Sector 1 issued approval and advised of civil aircraft with which Williamtown ATC needed to provide radar separation with their aircraft. Sector 1 also agreed to perform the co-ordination tasks with Sector 2 and Sydney Arrivals, which was correctly carried out.

Williamtown ATC then proceeded to recover their aircraft in accordance with the clearance issued by Sector 1, but as the FA18s were approaching civil airspace, Sector 1 advised of additional traffic VH-TAH whose track and altitude placed the aircraft in potential conflict with Shogun 1/2 [FA18].

Sydney Sector 1 believed that he had only co-ordinated an expectancy of approval with Williamtown ATC but Williamtown believed that they had received a clearance to transit the airspace.

As a result Williamtown ATC radar vectored its aircraft clear of VH-TAH and no breakdown in separation occurred.

Significant Factors

1. The co-ordination procedures for this section of airspace were complex and time consuming which led to confusion as to if an actual clearance was issued.