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On 19 September 2013, the pilot of a Beechcraft B300, registered VH-FIZ, was conducting calibration activities of ground-based navigation aids at Williamtown (Newcastle Airport), New South Wales.

During the calibration activities, the aircraft conducted a 7 NM (13.0 km) orbit around Williamtown. However, the Tower air traffic controller had intended the aircraft to hold south of Williamtown over land. At the same time, other aircraft were approaching Williamtown to land.

VH-FIZ tracked on the 7 NM arc towards, and then across the coast, on a converging path with a formation of four Boeing F/A18 aircraft that were on a visual approach to Williamtown. The formation flew directly below VH-FIZ with less than the required 1,000 ft separation.

What the ATSB found

The ATSB found that the applicability of a general requirement to conduct aviation risk assessments at Department of Defence aerodromes for complex, new, unusual or irregular activities was open to interpretation. This led to an absence of prior planning for the calibration activities, resulting in an air traffic control work-around on the day of the activities that did not address all related safety aspects. One work-around was that airspace over land usually controlled by Approach was transferred to the Tower. The resultant airspace controlled by the Tower was considerably larger than normal, resulting in the Tower controllers having difficulties visually monitoring the airspace and needing to rely on the surveillance display for situation awareness.

An instruction given to VH-FIZ to ‘orbit’ was insufficiently clear, resulting in the pilot misinterpreting it as permission to conduct a pre-planned 7 NM (13.0 km) orbit around Williamtown. As a result of the Tower controller’s assumption that VH-FIZ would remain in the area they intended, the aircraft was not adequately visually monitored by the controllers in the Tower, or monitored on radar by the Approach controller. This removed any chance of early detection of the impending aircraft conflict. When the Tower controller did detect the conflict, clear control instructions were not immediately given to either VH-FIZ or the F/A18s, leading to a loss of separation.

What's been done as a result

The Department of Defence took proactive action to improve the implementation of aviation risk management (AVRM) to ensure that AVRM plans developed for unusual or irregular operations, such as calibration operations, addressed staffing and traffic levels, coordination and workload.

Safety message

Although not guaranteeing the absence of aircraft separation incidents, prior planning for unusual or irregular operations can permit the development of robust air traffic control defences that address the specific hazards of that operation. Aircraft separation safety also relies on controllers issuing specific control instructions to all pilots, along with the provision of timely and relevant traffic information to pilots of aircraft identified to be in conflict.

Williamtown Visual Terminal Chart

Williamtown Visual Terminal Chart

Source: Airservices Australia

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The occurrence


Safety analysis


Safety issues and actions

Sources and submissions


Safety issue

AO-2013-160-SI-01 -  

Absence of prior planning

The applicability of a general requirement to conduct aviation risk assessments for complex, new, unusual or irregular activities was open to interpretation.

Safety issue details
Issue number:AO-2013-160-SI-01
Who it affects:Department of Defence air traffic services
Status:Adequately addressed

General details
Date: 19 September 2013 Investigation status: Completed 
Time: 1549 EST  
Location   (show map):near Williamtown Airport Investigation type: Occurrence Investigation 
State: New South Wales Occurrence type: Loss of separation 
Release date: 12 November 2015 Occurrence class: Airspace 
Report status: Final Occurrence category: Serious Incident 
 Highest injury level: None 
Aircraft 1 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: F/A18 x four 
Type of operation: Military 
Sector: Jet 
Damage to aircraft: Nil 
Departure point:Williamtown, NSW
Destination:Williamtown, NSW
Aircraft 2 details
Aircraft manufacturer: Hawker Beechcraft Corporation 
Aircraft model: B300 
Aircraft registration: VH FIZ 
Serial number: FL 779 
Type of operation: Aerial Work 
Sector: Piston 
Damage to aircraft: Nil 
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Last update 14 November 2018