Aviation safety issues and actions

Military ATS risk

Issue number: AR-2012-034-SI-01
Who it affects: All civilian aircraft operations into military controlled airspace
Issue owner: Department of Defence
Transport function: Aviation: Airspace management
Background: Investigation Report AR-2012-034
Issue release date: 18 October 2013
Current issue status: Adequately addressed
Issue status justification:

The rate of LOS incidents at Darwin, Townsville and Williamtown have reduced substantially since the original study period. While there is still an elevated risk of a LOS incident at Darwin terminal and tower airspace due to pilot actions, the ATSB has noted the unique mix of traffic at Darwin compared to other Class C airports, and noted the Department of Defence commitment for an ongoing review of the traffic management plan at Darwin. Ongoing review may provide further opportunities to reduce the LOS incident rate at Darwin, in particular, those involving pilot errors.

Safety issue description

There was a disproportionate rate of loss of separation incidents which leads to a higher risk of collision in military terminal area airspace in general and all airspace around Darwin and Williamtown in particular. Furthermore, loss of separation incidents in military airspace more commonly involved contributing air traffic controller actions relative to equivalent civil airspace occurrences.

Response to safety issue by: Department of Defence

The Department of Defence takes all losses of separation and losses of separation assurance seriously and investigates all incidents to identify causes and areas that can be improved in order to mitigate against further occurrences. To reduce the potential for separation occurrences, Defence are reviewing the implementation of the traffic management plans at Darwin, Townsville, and Williamtown to improve the effect of strategic separation techniques. These reviews will also be used to highlight any current airspace constructs that inhibit the controller’s ability to provide optimum separation assurance. Defence has also recently published an internal capability improvement plan that focuses on increasing experience levels at Defence air traffic locations. To improve our ability to respond to potential losses of separation, Defence has enhanced the School of Air Traffic Control simulator packages to provide greater exposure to compromised separation occurrences, with the trainee being assessed on their ability to apply compromised separation recovery. Defence has also added both theoretical and practical assessment to local training packages regarding scanning for possible losses of separation and applying compromised separation recovery techniques when required.


ATSB comment in response

The ATSB acknowledges the intended action by the Department of Defence, but considers that a broader review of Defence ATC processes and risk controls should be undertaken, including analysis of ATS related occurrence data, training, staffing and ATS infrastructure to ensure the reasons for the disproportionate risk of loss of separation incidents, and the relative higher level of controller actions contributing to these occurrences, are well understood and any additional appropriate action can be taken to minimise future risk. As such, the ATSB is issuing the following recommendation.


Action number: AR-2012-034-SR-014
Action organisation: Department of Defence
Date: 18 October 2013
Action status: Released

The Australian Transport Safety Bureau recommends that the Department of Defence undertake a review of all processes and risk controls in place to reduce both the disproportionate risk of loss of separation incidents in military terminal area airspace in general and all airspace around Darwin and Williamtown in particular, and the relatively more common contributing air traffic controller actions.

Additional correspondence

Response date: 20 January 2014
Response from: Department of Defence
Action status: Monitor
Response text:

In accordance with Section 25A (2) of the Transport Safety Investigation Act 2003, I hereby advise the ATSB that Defence does not agree with the Safety Recommendation AR- 2012-034-SR-014. The report insufficiently acknowledges the unique context of military operations and the role of the Defence Aviation Safety system. Despite the vast majority of incidents occurring in civil airspace, the report remains negatively biased against military airspace and is based on a subjective comparison of military and civil Air Navigation Service Providers. Therefore, Defence disagrees with the report's conclusions and recommendations.

Whilst Defence does not support the report, as a proactive safety organisation we will continue to implement changes to further enhance safety and commit to reducing our loss of separation rate. Defence will continue to improve air traffic control workforce capability, increased practical simulator training and update air traffic management plans. Additionally, a joint Civil Aviation Safety Authority-Defence aeronautical study will be conducted of RAAF Base William town in 2014, with the scope for future joint studies at other locations.

ATSB comment:

The ATSB remains concerned that the Department of Defence does not accept that, although military controlled airspace represents only a small proportion of total Australian controlled airspace, the risk associated with loss of separation is disproportionally high relative to the number of aircraft movements compared to civil controlled airspace.

The ATSB welcomes the promised joint-safety study at Williamtown in 2014 and other defence airfields in the future. Loss of separation involving civilian aircraft in military controlled airspace will continued to be closely monitored by the ATSB until this time. The Safety Recommendation will remain open until the ATSB has assessed the outcomes of the review at Williamtown.

Response date: 06 October 2016
Response from: Department of Defence
Action status: Monitor
Response text:

Defence has taken a number of steps to respond to recommendation and have been providing periodic updates to the Aviation Policy Group. A response documenting all safety actions will be provided to the ATSB in December 2016.

Response date: 06 September 2017
Response from: Department of Defence
Action status: Monitor
Response text:

Defence continues to implement the recommendations associated with the October 2015 Joint CASA and RAAF Aeronautical Study of Williamtown Airspace. While many of the recommendations have already been implemented, numerous recommendations primarily concern civil aviation; such as those associated with civil instrument flight procedures, air routes and civil-military traffic management planning. As many of the recommendations fall outside the purview of Defence, in November 2016 the Aviation Implementation Group agreed to establish a working group to develop a strategic implementation plan for all recommendations requiring inter-agency collaboration and to provide periodic updates to the Aviation Implementation Group. The Aviation Implementation Group has also recognised that an absence of national policy guidance on which agency is responsible for design and maintenance of civil instrument flight procedures is another area that requires resolution to inform the way forward.

The strategic implementation plan will inform further Defence response to AR-2012-034-SI-01, as it pertains to initiatives that will further reduce the risk of loss of separation incidents. Defence looks forward to providing another update to the ATSB following the next Aviation Implementation Group which is scheduled for November 2017.

Response date: 27 June 2018
Response from: Department of Defence
Action status: Closed
Response text:

1. Since the last update in response to the ATSB Report AR-2012-034, Defence has continued to progress several initiatives in relation to Darwin, Townsville and Williamtown.

2. Traffic Management Plans (TMPs) have been implemented for both Darwin and Townsville. In the case of Darwin, this was in 2013 and for Townsville in 2014. Both sites worked with Airservices Australia on the development of the plans, which have introduced a significant level of strategic separation principles for civil and military aircraft operating to and from both aerodromes.

3. For Darwin, improved coordination with Brisbane Air Traffic Control allows enhanced flow management, thereby reducing delays to airlines and enabling better integration of departures and low level arriving aircraft. VFR routes and level assignments provide more efficient separation with IFR departures and arrivals whilst ensuring VFR routes avoid Restricted Airspace. The improvements also provide for improved utilisation of Darwin's runway configuration and Land and Hold Short Operations (LAHSO) clearances. This allows Darwin to ensure that all aircraft remain separated, sequenced with predictable tracking and timings.

4. For Townsville, the TMP continues to mature. The current plan managed via an AIP Supplement and is focused on the use of Standard Instmment Departures (SIDs) for departing IFR aircraft, generally B737 and above, and strategic sequencing points for arriving aircraft. The next iteration of the TMP will introduce Standard Terminal Arrival Routes and upgraded SIDs thereby providing increased strategic separation principles. These will now be updated through the existing AIRAC cycle and are on schedule for publication in November 2018.

5. The key tenets of both plans are the introduction of strategic separation principles for both aerodromes. They enable predictability and certainty for civil aircraft operations as well as flexibility for military aircraft, in particular fighter type aircraft.

6. At Williamtown, Defence continues to actively progress the recommendations and findings of the October 2015 Joint CASA and RAAF Aeronautical Study of Williamtown Airspace. As previously advised, many of the recommendations fall outside the purview of Defence, however through the cooperative engagement with the Aviation Implementation Group (AIG), of which Defence is a member, there continues to be significant progress being made towards finalisation. The two remaining recommendations purely within Defence's ability to finalise, re-alignment of two airspace boundaries, will be completed by Nov 18 to allow publication in the May 19 AIRAC.

7. The 14 open recommendations require the redesign of civil IFP, the possible redesign of restricted Airspace inside 25nm of Williamtown as potential CTA (pending CASA advice), the design of SIDs, STARs and air routes all of which would be incorporated into a Williamtown Traffic Management Plan. This is being progressed by the Williamtown Airspace Working Group, which provides regular updates to the AIG, however as the tasks are all inter-related they cannot be completed independently. Airservices Australia has
committed to work on the redesign of civil IFP and will sequence this into their work schedule. Currently, this work is not expected to commence until late 2019 with finalisation and publication in AIP not expected until the November 2021 AIRAC at the earliest.

8. The TMPs at both Darwin and Townsville will continually be reviewed as part of normal business practice. Defence will not be providing further updates on these plans. Defence will continue to provide updates on progress at Williamtown, with the next update
coming following confirmation that all work required to progress the TMP has been completed and better fidelity of when publication is expected.

9. Defence remains committed, as an ANSP, to the continued provision of safe and efficient Air Base Air Traffic Services. CASA participates, in an observer capacity, in the Defence Air Traffic Control Operational Airworthiness and Air Traffic Control Operational Evaluation processes. Safety for all airspace users remains out highest priority.

ATSB comment date: 26 June 2019
ATSB comment:

The ATSB notes the significant reviews conducted by the Department of Defence in relation to this recommendation and the associated safety actions. Analysis of the rates of loss of separation incidents in the six years 2013-2018 has shown an associated reduction in the rate of loss of separation incidents in terminal and tower airspace at Darwin, Townsville and Williamtown, relative to the original study period of 2008-2012. For Townsville and Williamtown, the LOS incident rate per 100,000 aircraft movements was comparative to the levels of civil-controlled Class C airport LOS rates used in the original analysis. However, for Darwin, the rate of LOS incidents is still above the levels of civil-controlled Class C airport LOS rates used in the original analysis.

The LOS incidents that ATC actions contributed to, all three locations had a lower rate of reported ATC contributed LOS incidents from 2013 to 2018 compared to the original safety issue period 2008 to 2012. For Darwin, there has been an increase in the rate of LOS incidents from pilot actions across the time period.

Last update 27 June 2019