Aviation safety investigations & reports

Loss of separation involving a Cessna Aircraft Company 550, VH-ING and The Boeing Company 737-376, VH-TAY, 46km E Cowra, NSW on 2 March 1998

Investigation number:
199800616
Status: Completed
Investigation completed

Summary

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The Cessna Citation (C550) was on climb to flight level 310 (FL310), but had been restricted to FL280 due to opposite direction traffic on descent to FL290. The Sector 16 controller had coordinated the planned flight level with the next sector and had notated the flight strip accordingly. A following Boeing 737 (B737) was on the same track and had planned to climb to FL350, but had also been restricted to FL280 due to the same conflicting traffic. The controller had also coordinated this flight with the following sector and had notated the flight strip accordingly. The B737 reached FL280 first and began to increase speed as the aircraft maintained level flight. At this time the slower C550 was approximately 25 NM ahead of the B737, but still climbing. An opportunity to establish positive vertical separation was available at this time but the controller did not invoke separation assurance techniques. The controller had intended to climb both aircraft to their respective flight planned levels after they had passed the opposite direction traffic, and expected to maintain the 5 NM radar separation standard prior to that event. Changes to airspace procedures had taken place 3 days prior to the occurrence and it was the controller's first shift involving the new procedures since the introduction of Class "E" airspace. He had been on duty just 30 minutes when he received his first request for a clearance involving "E" airspace. This request resulted in him having to perform coordination tasks with both Flight Service and Sector 19. The consequent workload due to his unfamiliarity with the new procedures resulted in his attention being diverted from the radar display, as the B737 closed on the C550. The C550 subsequently levelled at FL280. A controller not performing tasks related to Sector 16 noticed the rate of closure between the C550 and the B737, and brought this to the attention of the Sector 16 controller who immediately issued a radar vector to the crew of the B737. As the aircraft passed, the horizontal separation reduced to approximately 1/2 NM. The crew of the B737 did not sight the C550. Radar analysis indicated that the closing speed varied between 70 and 220 kts. It had been planned that all Sector 16 controllers were to have undergone 5 simulator exercises prior to the implementation of "E" airspace. However, due to time constraints and technical difficulties, only 4 exercises had been developed. An agreement had been reached for all Sector 16 controllers to receive those 4 exercises. However, the controller on duty had only experienced 2 complete and 1 "over the shoulder" simulator exercises at the time of implementation. Moreover, the changes issued by the Civil Aviation Safety Authority, 7 days prior to implementation, resulted in a new version of Local Instructions for Sector 16 only becoming available to the controller 4 days before the occurrence. This limited the time available for adequate training of air traffic controllers. SAFETY ACTION As a result of this occurrence, the Bureau of Air Safety Investigation is currently investigating a perceived safety deficiency. The deficiency identified relates to air traffic controller training. Any safety output issued as a result of this analysis will be published in the Bureau's Quarterly Safety Deficiency Report.
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General details
Date: 02 March 1998   Investigation status: Completed  
Time: 6:35 ESuT    
State: New South Wales   Occurrence type: Loss of separation  
Release date: 07 August 1998   Occurrence category: Incident  
Report status: Final    

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model 550  
Aircraft registration VH-ING  
Sector Jet  
Damage to aircraft Nil  
Departure point Bankstown NSW  
Destination Adelaide SA  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737-376  
Aircraft registration VH-TAY  
Sector Jet  
Damage to aircraft Nil  
Departure point Sydney NSW  
Destination Adelaide SA