Losses of separation assurance involving Airbus A330-243, PK-GPO and Airbus A330-341, PK-GPA, near ATMAP (IFR reporting point), Western Australia, on 31 March 2012

What happened

On 30 March 2012, Airservices Australia was unable to resolve two short-notice controller absences for night shift coverage of the Kimberley and Cable airspace sectors, located over north-western Australia. A contingency plan was activated, and a Temporary Restricted Area (TRA) initiated for that airspace from 0015 to 0515 Eastern Standard Time on 31 March.

Two aircraft separately entered the TRA without the knowledge of Airservices personnel. An Airbus A330 registered PK-GPA, on a flight from Denpasar, Indonesia to Melbourne, Victoria, was detected at 0500 when the flight crew contacted a Melbourne Centre controller because their aircraft was at the Brisbane/Melbourne Flight Information Region (FIR) boundary after transiting the TRA. The second aircraft, an A330 registered PK-GPO, on a flight from Denpasar to Sydney, New South Wales, was detected at 0641, when the crew contacted Melbourne Centre at the FIR boundary. The aircraft had been operating in controlled airspace for 86 minutes, without the knowledge of any controllers. The minimum standards for separation from other aircraft were met, but both situations constituted losses of assurance that separation would be maintained.

What the ATSB found

Overall, 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. 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 concluded that a number of procedures and processes were not fulfilled on the night of the occurrence and identified four safety issues: Airservices’ process for ensuring that all aircraft operating in the TRA were known to ATS; selection and preparation of personnel for the Contingency Response Manager role; the contingency plan testing and review process; and the absence of a defined process for recording the actual hours worked by Air Traffic Control Line Managers.

What's been done as a result

Airservices has revised its contingency plan documentation and procedures. In addition, its updated Fatigue Risk Management Requirements have addressed the recording and monitoring of the actual hours worked by Air Traffic Control Line Managers.

The ATSB is not satisfied that Airservices has adequately addressed the identified safety issues regarding processes for managing a Temporary Restricted Area to ensure that all aircraft were known to air traffic services and contingency plan testing and review effectiveness. As a result, the ATSB has made formal recommendations to Airservices.

The operator of the A330 aircraft, Garuda International, specified that, as the use of procedures associated with TRA activation was an infrequent requirement and not practiced in daily operations, it would ensure the procedures were reviewed as part of check and training programs.

Safety message

The occurrence provides a timely reminder to all organisations operating in high reliability systems of the importance of having multiple risk controls in place to effectively manage rare combinations of events during abnormal situations, and to regularly review the effectiveness of these controls.