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A Brasilia VH-XFZ was on a visual approach to Cairns from the south-east and was tracking to left base runway 15. A Citation VH-PSU departed from runway 15 without a separation standard being applied by the approach controller between the two aircraft. The aircraft passed with approximately 500 ft difference in their altitudes when there was less than 3 NM laterally between them.

The controller could have either coordinated the use of a visual separation procedure with the aerodrome controller or the crew of either aircraft, or employed a 1,000 ft vertical separation standard or a 3 NM radar standard to ensure that the aircraft were separated.

The investigation revealed that the controller was aware that a separation standard was required. This was confirmed by the controller's request to the pilot of XFZ to report seeing PSU that was shortly to depart. However, subsequent actions limited the ability of the pilot of XFZ to comply with the request. If this sighting had been achieved, it would have allowed the transfer of separation responsibility from the controller to the pilot. This procedure did not provide separation assurance and was a "fail-unsafe" procedure as it relied solely on the pilot's ability to to see the other aircraft and limited the controllers' options should the pilot be unable to comply.

When the crew of XFZ were unable to sight PSU the controller then monitored PSU's climb performance and assessed that the aircraft would not collide. However, vertical separation reduced to less than the standard when there was no radar standard being applied.

The use of a radar standard was constrained by the disposition and intended tracks of the aircraft. In this situation, the Manual of Air Traffic Services (MATS), 9-2-1, paragraph 19 states that a procedural separation standard shall be applied. Also, the controllers actions did not comply with MATS 4-1-1, paragraphs 4-6 which places greater emphasis on traffic planning and conflict avoidance by controllers instead of conflict resolution. The use of separation assurance techniques by the controller would have ensured the separation of the aircraft.


As a result of this and other occurrences, the Australian Transport Safety Bureau (formerly BASI) is currently investigating a safety deficiency. The deficiency relates to aspects of separation assurance techniques within air traffic control.

Any safety output issued as a result of this analysis will be published in the Bureau's Quarterly Safety Deficiency Report.

General details
Date: 09 November 1999 Investigation status: Completed 
Time: 0820 hours EST  
Location   (show map):9 km ENE Cairns, (VOR) Investigation type: Occurrence Investigation 
State: Queensland Occurrence type: Loss of separation 
Release date: 26 April 2000 Occurrence class: Airspace 
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
Aircraft 1 details
Aircraft manufacturer: Embraer-Empresa Brasileira De Aeronautica 
Aircraft model: EMB-120 
Aircraft registration: VH-XFZ 
Serial number: 120140 
Type of operation: Air Transport Low Capacity 
Damage to aircraft: Nil 
Departure point:Townsville, QLD
Destination:Cairns, QLD
Aircraft 2 details
Aircraft manufacturer: Cessna Aircraft Company 
Aircraft model: 560 
Aircraft registration: VH-PSU 
Type of operation: Aerial Work 
Damage to aircraft: Nil 
Departure point:Cairns, QLD
Departure time:0802 hours EST
Destination:Brisbane, QLD
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Last update 13 May 2014