In the evening of 4 July 2013 at 2040 Eastern Standard Time, a loss of separation occurred between an Airbus A320 operated by Jetstar, registered VH‑VFJ (VFJ), conducting a missed approach from a VOR approach to runway 36 at Avalon Airport, Victoria and a Bell 412, registered VH‑VAO (VAO), departing Avalon for Warrnambool, Victoria.

As the air traffic control tower at Avalon was closed, the airspace immediately above Avalon to a height of 700 ft was classified as Class G. From 700 ft to 4,500 ft the airspace was Class E, and above that was Class C. Air traffic services were being provided by a controller also responsible for Melbourne Departures. Aircraft in Class G were required to make broadcasts on the Common Traffic Advisory Frequency (CTAF). Due to the airspace configuration, pilots of IFR aircraft operating into and out of Avalon were required to monitor both the Avalon CTAF and the Avalon Approach frequency.

As a result of this occurrence, Jetstar has advised the ATSB that a technical newsletter will be sent to company flight crew highlighting the incident and emphasising the joint responsibility for maintaining separation assurance; providing guidance with regard to correct controller / flight crew interactions, specifically in relation to a clearance to leave and re-enter controlled airspace in the event of a missed approach at CTAFs with low overlying controlled airspace; and providing guidance with regard to controller expectation of the transfer of responsibility for separation from within the CTAF (on approach) to controlled airspace (in the event of a missed approach).

As a result of this occurrence, Airservices is currently undertaking a review of the risk profile associated with Avalon operations and airspace design. Of concern are the small layers of differing airspace classes with different service levels and frequency requirements. Pending the findings of the review, Airservices may request that the Civil Aviation Safety Authority (CASA) conduct an aeronautical study of the airspace surrounding Avalon Airport.

This incident demonstrates that, while expediting traffic is an important objective for a controller, safety must always be the first consideration. The incident also highlights the joint separation and communication responsibilities between flight crews and controllers in the Avalon airspace when Avalon Tower is not active.


Aviation Short Investigation Bulletin - Issue 23