Aviation safety issues and actions

Disabling of Australian Defence Air Traffic System conflict alerts

Issue number: AO-2011-011-SI-02
Who it affects: All RAAF Base Williamtown based Department of Defence air traffic controllers
Issue owner: Department of Defence
Transport function: Aviation: Airspace management
Background: Investigation Report AO-2011-011
Issue release date: 07 March 2012
Current issue status: Adequately addressed
Issue status justification:

Department of Defence trialled the reactivation of the ADATS confluct alert function, at Williamtown, for 2 months. During that period, they identified a number of factors that indicated that it would be more efficient and effective to diable the conflict alert during military operations. However, the ADATS conflict alert function is re-enabled when military flying ceases each day.

Safety issue description

An important alerting function within the Australian Defence Air Traffic System had been disabled at Williamtown to prevent nuisance alerts.

Proactive Action

Action number: AO-2011-011-NSA-007
Action organisation: Department of Defence
Date: 07 March 2012
Action status: Closed

Following the incident, a conflict alert trial was conducted at Williamtown to validate the safety case which had determined that, due to numerous unavoidable spurious alarms, the conflict alert function in ADATS should be disabled. After hazard identification and risk assessment, simulator testing of developed procedures and training of APR controllers commenced with the trial running for 2 months (25 Jul 2011 - 30 Sep 2011) across various traffic conditions.

Over the period, excessive alarms were activated of which were as a result of a lack of separation assurance or a loss of separation; however, the subsequent investigations indicated that the alert did not assist in the identification nor resolution of the conflicts.

Controllers were found to be distracted by the additional procedures required to avoid false-alarms, deliberately controlling inefficiently to avoid false alarms or accepting false-alarms resulting in desensitisation.

Consequently, the trial outcome was to discontinue the use of CA during military operations, however it is enabled upon cessation of military flying activity at Williamtown.

ATSB comment:

DoD took appropriate action in trialling the re-enablement of the ADATS conflcit alert function at Williamtown. Even though they have identified that it is more effective had the conflict alert function disbaled, due to a number of factors, the alert function is being ebaled when there is no military flying.

Last update 23 March 2016