The aircraft departed Maroochydore on climb to a cleared level of flight level (FL) 260. After being transferred to Brisbane Approach (North), the aircraft requested an amended level of FL 240.
The Approach (North) controller cleared the the aircraft to maintain FL 240. Later, on transfer to Brisbane Sector 1, the aircraft reported on climb to FL 240. However, the Sector 1 controller had not been notified of the level change and was expecting the aircraft at FL 260. Before the aircraft departed Maroochydore, there was a request for the aircraft to track direct to Singleton instead of the usual route via Farrel (a reporting point south-east of Maroochydore).
The direct track took the aircraft close to overhead Brisbane during its climb. The Approach (North) controller agreed with the request. Potential conflictions with the aircraft included two aircraft inbound to, and two outbound from, Brisbane. The request for the amended level was made while these aircraft were being processed and the controller annotated FL 240 on the flight strip but neglected to co-ordinate this information with Sector 1. It appears possible that the increased workload resulting from the aircraft being cleared direct to Singleton might have been sufficient to cause the controller to omit to conduct the co-ordination with Sector 1. There was no requirement for the controller to approve the level change requested by the aircraft. At the time of the request, the aircraft was some distance from top of climb and the controller could have controlled his workload better by deferring the request.
SIGNIFICANT FACTORS:
1. The controller agreed to a request for direct tracking which had a significant impact on his workload. 2. The controller unnecessarily approved a request from the aircraft for a level change at a time of high workload. 3. Probably as a result of 1. and 2. above, the controller failed to co-ordinate the change of level with the next sector.
SAFETY ACTION:
On 19 August 1993, an instruction was issued by the Manager Brisbane AACC amending the procedural requirements so that controllers are now required to provide an adjacent unit or position with advice of an amended level whilst effecting handover. In response to this, and other recent incidents in this area, the Bureau of Air Safety Investigation, in co-operation with the Civil Aviation Authority, have conducted further investigations, resulting in the publication of Investigation Report BS/930154 titled, "An Investigation Of Systemic Factors Underlying Air Safety Occurrences In the Brisbane Area Approach Control Centre."