Airservices Australia and Garuda Indonesia have changed a series of procedures following two loss of separation assurance incidents during the early morning of 20 March 2012.

In an investigation report, the Australian Transport Safety Bureau (ATSB) said that although neither Garuda A330 aircraft, bearing registration PK-GPA and PK-GPO, lost separation, they flew in controlled airspace for 86 minutes without the knowledge of any Australian air traffic controllers.

PK-GPA was operating on the Bali Denpasar-Melbourne sector, and PK-GPO was operating on the Bali Denpasar-Sydney sector.

The issue stemmed from Airservices Australia’s establishment that evening of a Temporary Restricted Area (TRA) covering the Kimberley and Cable airspace sectors. Two controllers were assigned to the sectors that evening, but they both missed work citing personal reasons.

After exploring various options, Airservices saw no option but to establish the TRA.

“Airservices had many risk controls in place to manage the situation where it was unable to provide the published air traffic services (ATS) and had to activate a TRA,” says the ATSB report.

“In this case, a TRA had to be activated at short notice in airspace adjacent to an international ATS provider, and a range of actions by operational personnel did not conform to expectations. Airservices’ risk controls were not robust enough to effectively manage this situation and ensure they would be made aware of all aircraft that were operating within the TRA.”

The ATSB report cited a number of problems, mainly with Airservices’ processes and review procedures. These failures, in addition to procedural lapses on the part of the flight crews, resulted in the aircraft effectively being hidden from air traffic control for nearly 90 minutes.

As a result of the incident, Airservices revised its contingency documents and procedures. Nonetheless, the ATSB still believes Airservices has yet to rectify the issue, and has issued formal recommendations.

Garuda, for its part, will provide more training emphasis on TRAs in its flight crew training programmes.

Source: Cirium Dashboard