Aviation safety investigations & reports

Breakdown of separation - Boeing B737, VH-VBK and Israel Aircraft Industries Westwind 1124, VH-AJG, 22 km South of Williamtown (Newcastle Airport), NSW, 1 February 2011

Investigation number:
Status: Completed
Investigation completed


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At 1305 Eastern Daylight-saving Time on 1 February 2011, a breakdown of separation occurred 22 km south of Williamtown (Newcastle Airport), New South Wales between a Boeing B737-7Q8 (737), registered VH-VBK, and an Israel Aircraft Industries Ltd Westwind 1124 (WW24) aircraft, registered VH-AJG. Both aircraft were in communication with and under the jurisdiction of Department of Defence (DoD) air traffic controllers based at Williamtown.

Separation between the aircraft reduced to 0.7 NM (1.3 km) on radar and 400 ft vertically when the required separation standard was 3 NM (5.6 km) or 1,000 ft. The vertical separation achieved was as a result of the 737 flight crew responding in accordance with a resolution advisory provided by their aircraft's traffic alert and collision avoidance system.

The investigation identified a series of errors by the Williamtown Approach controllers involving separation assurance, coordination and communication, and compromised separation recovery.

The investigation also identified three safety issues. The DoD advised that they reviewed and amended Williamtown procedures, introduced compromised separation recovery techniques training and trialled use of the conflict alerting function in the Australian Defence Air Traffic System at Williamtown.

Download Final report
[Download  PDF: 635KB]
Alternate: [Download  DOC: 704KB]
General details
Date: 01 February 2011   Investigation status: Completed  
Time: 1305 ESuT    
Location   (show map): Williamtown Airport, South 22 km   Investigation type: Occurrence Investigation  
State: New South Wales   Occurrence type: Loss of separation  
Release date: 07 March 2012   Occurrence class: Airspace  
Report status: Final   Occurrence category: Serious Incident  
  Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VBK  
Serial number 30648  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Williamtown, NSW  
Destination Melbourne, Vic  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Israel Aircraft Industries Ltd  
Aircraft model 1124  
Aircraft registration VH-AJG  
Serial number 281  
Type of operation Charter  
Damage to aircraft Nil  
Departure point Nowra, NSW  
Destination Williamtown, NSW  
Last update 14 November 2018