Aviation safety issues and actions

Risk controls for manual processing of transponder code changes

Issue number: AO-2012-131-SI-01
Who it affects: All Darwin Approach Supervisor, Approach and Planner rated Joint Battlefield Airspace Controllers
Issue owner: Department of Defence
Transport function: Aviation: Other
Background: Investigation Report AO-2012-131
Issue release date: 02 October 2014
Current issue status: Adequately addressed
Issue status justification:

The ATSB is satisfied that the safety action undertaken, and action in progress, will satisfactorily address the safety issue.

Safety issue description

The Australian Defence Air Traffic System (ADATS) did not automatically process all system messages generated by The Australian Advanced Air Traffic System. In cases where transponder code changes were not automatically processed, the risk controls in place were not able to effectively ensure that the changes were identified and manually processed.

Proactive Action

Action number: AO-2012-131-NSA-033
Action organisation: Department of Defence
Date: 02 October 2014
Action status: Closed

A Safety Advisory dated 18 March 2013 was distributed to Department of Defence (DoD) controllers on 19 March 2013. The document referenced the findings of the Directorate of Defence Aviation and Air Force Safety’s investigation. The documented purpose of the Safety Advisory was to address three internal recommendations:

  • 44 Wing should highlight to controllers the importance of the appropriate and timely actioning of all messages sent to the Australian Defence Air Traffic System (ADATS) Problem Message Queue (PMQ)
  • 44 Wing should implement measures to ensure that all Planner controllers confirm that correct transponder codes are allocated in the ADATS flight plan
  • 44 Wing should reinforce to controllers to take immediate action on all conflict alert (CA) and predicted conflict alert (PCA) alarms, and, only once confirmed that no conflict is present or that particular alarm confirmed as spurious, can a lesser action be taken.

One of the intents of the Safety Advisory was to provide awareness to controllers that the PMQ needed to be thoroughly checked prior to inadvertent deletion of important information.

In addressing the recommendation for the implementation of measures to ensure the correct allocation of transponder codes, the Safety Advisory advised controllers to ‘consciously ask themselves what needs to be done with the information they receive during coordination between different agencies.’

The document also highlighted to controllers the importance of ADATS conflict alerts and instructed controllers that all PCA and CA alarms were to be considered legitimate and that:

…all necessary control instructions to ensure separation between conflicting aircraft are to be issued in the interim until the alarm is proven to be something other than legitimate.

On 31 July 2014, the DoD also advised that 44 Wing would work with Airservices Australia to ascertain if the implementation of change messaging between the ADATS and The Australian Advanced Air Traffic System was feasible.

ATSB comment:

The safety action taken by DoD required that individuals be more vigilant in their processing of Problem Message Queue (PMQ) traffic and coordinated details but did not address the influence of increased workload in the Planner position that could result in not all tasks, including the manual processing of messages from the PMQ, being completed in a timely manner. However, the introduction of Flight Data Operators (FDOs) at a number of Defence air traffic control establishments may reduce workload in the Planner position and allow more time for the processing of PMQ traffic and coordinated details. As such this safety action, in conjunction with the provision of FDOs should address this safety issue.

Last update 20 July 2015