Aviation safety investigations & reports

de Havilland Canada DHC-7-102, VH-UUM, 13 km WSW Cairns, Aero. QLD, 17 November 1999

Investigation number:
Status: Completed
Investigation completed


The crew of the Dash 7, registered VH-UUM, were cleared to track visually via Kuranda. The crew of the Cessna 310, registered VH-XXT, were cleared to track visually via Stoney Creek. Both aircraft had flight planned IFR and were entitled to positive air traffic control separation. Such separation was not provided and the required radar separation standard of 3 NM between the two aircraft was infringed. The investigation revealed that the strategy for separation employed by the approach controller did not provide a separation standard. Radar separation was an option, in accordance with the Manual of Air Traffic Services (MATS), 9-2-1, paragraph 19, if the departing aircraft had been issued a standard radar departure. Such a departure was not provided. Moreover, because vertical separation had not been employed, the controller had to rely on lateral separation to ensure the aircraft did not conflict. However, lateral separation would not exist if both aircraft were simultaneously east of a line Stoney Creek-Kuranda. There was no separation assurance. MATS 4-1-1, paragraphs 4-6 place significant emphasis on the need for controllers to apply separation assurance techniques. Realising the potential confliction after take-off, the controller attempted to establish a visual sighting of the departing aircraft by the crew of the arriving aircraft. The visibility was reduced due to smoke haze, making a sighting unlikely. If a sighting had been achieved, it would have allowed the transfer of separation responsibility from the controller to the pilot. The crew of the arriving aircraft were unable to sight the departing aircraft. The controller then requested the crew of the arriving aircraft to make a right orbit but the crew were unable to comply due to high terrain. The crew suggested a left orbit, which was agreed to by the approach controller. The left orbit however, further reduced the distance between the two aircraft. The crew of the departing aircraft then sighted the arriving aircraft, with the assistance of the aircraft's TCAS, and were able to visually maintain separation. Vertical separation was reduced to 100 ft when the aircraft were 1.5 NM apart. The required radar separation was 3 NM or 1,000 ft vertically.

Safety Action

As a result of this and other occurrences, the Australian Transport Safety Bureau, formerly the Bureau of Air Safety Investigation, is currently investigating a safety deficiency. The deficiency relates to aspects of separation assurance techiques 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: 17 November 1999   Investigation status: Completed  
Time: 1728 hours EST    
Location   (show map): 13 km WSW Cairns, Aero.    
State: Queensland   Occurrence type: Loss of separation  
Release date: 24 December 1999   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer de Havilland Canada  
Aircraft model DHC-7  
Aircraft registration VH-UUM  
Serial number 043  
Type of operation Charter  
Damage to aircraft Nil  
Departure point Cairns, QLD  
Destination Mareeba, QLD  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model 310  
Aircraft registration VH-XXT  
Serial number 310R1617  
Type of operation Unknown  
Damage to aircraft Nil  
Departure point Mareeba, QLD  
Destination Cairns, QLD  
Last update 13 May 2014