Breakdown of co-ordination involving a Cessna 500, VH-SOU, 56 km south of Canberra VOR, Australian Capital Territory, on 11 July 1999

The identification and planned level (FL290) of the aircraft was coordinated with the Melbourne Sector 12 controller. The aircraft was observed on radar to maintain FL250. The amended level was not coordinated with sector 12. There was no infringement of separation standards. 

An investigation by Airservices Australia found:

1. that the sector did not have specific procedures to ensure that controllers on adjacent sectors were notified when sector 12 opened/closed,

2. the Hume sector controller did not coordinate the change of level with the sector 12 controller,

3. a console display notifying active sectors had not been updated, and

4. that the display did not provide an indication of combined sectors. Consequently, there had been some confusion in relation to the required coordination between sectors. The investigation is continuing.