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A332 / A333, en-route, North West Australia, 2012

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Revision as of 21:26, 21 March 2015 by Integrator1 (talk | contribs)


On 31 March 2012 an Airbus A330-300 (PK-GPA) being operated by Garuda on a scheduled passenger flight from Bali (Denpasar) to Melbourne and an Airbus A330-200 (PK-GPO) being operated by Garuda on a scheduled passenger flight from Bali (Denpasar) to Sydney were both independently involved in losses of separation assurance because of issues arising from the short notice temporary implementation of TIBA procedures in an area of upper airspace following due to a shortage of controllers.


An Investigation was carried out by the Australian Transport Safety Bureau (ATSB).

It was noted that the basis for the determination that a Serious Incident had occurred was that two aircraft had operated in controlled airspace without ATC awareness because of issues related to the temporary implementation of TIBA procedures in a TRA when the provision of normally mainly procedural ATC service in an area of upper airspace controlled from Brisbane ACC could not be maintained. An overview of the airspace involved is shown below:

The Kimberley (KIY) and Cable (CBL) sectors where the Temporary Reserved Area was implemented and TIBA procedures notified showing the adjacent FIRs (reproduced from the Official Report)

It was established that on the evening of 30 March 2012, the two controllers who had been rostered to man the combined Kimberley (KIY) and Cable (CBL) sectors from 2300 that day until 0615 on 31 March had both called in at short notice to advise that they "were unable to attend for their shift". In both cases this notification was described as for "a legitimate personal reason". No replacements could be found, although it was possible to cover the beginning and end of this shift period by obtaining agreements from controllers on the shifts prior to and following the un-covered period to respectively slightly extend / begin earlier their duty periods. Contingency plans to designate a TRA which would temporarily withdraw ATS and substitute TIBA procedures between 0015 and 1615 local time (EST) on 31 March were activated and a NOTAM was issued to advise of these arrangements. The necessary regulatory approval was also obtained.

Whilst the TRA was in place, the console for the affected sectors was monitored by an upper airspace line manager at the Brisbane ACC who was designated as the Contingency Response Manager (CRM).

A Garuda Airbus A330-300 (PK-GPA) departed from Bali (Denpasar) at 0237 EST on a scheduled passenger flight to Melbourne and climbed to its flight planned cruise level of FL 370. The crew were aware of the Notice To Airmen and the en route airspace where TIBA procedures would be required. The TRA was entered at approximately 0310 EST without ATC being aware. The flight crew stated subsequently that during the flight through the TRA, they had conducted all-stations broadcasts on frequency 128.95 as required.

However, they had not made a position report to ATC on the next (Melbourne ACC) 15 minutes prior to leaving the TRA in order to obtain a clearance before entering the controlled airspace which bordered the TRA, which was required as part of the notified TIBA procedures and only reported doing so concurrently with leaving the TRA and re-entering controlled airspace at 0500 EST. Consequently, the controller responsible for the airspace involved was unaware of it and a Loss of Separation Assurance (LOSA) occurred.

Further Reading