On 9 August 2012 at 1235 Eastern Standard Time, a breakdown of separation occurred between a Raytheon Beech 200, registered VH-FDD (FDD) operating under the callsign FLYDOC 423, and a Raytheon Beech 350, operating under the callsign DINGO 008, near Cooktown, Queensland. An air traffic controller had issued clearance for FDD, tracking north, to climb to flight level (FL) 300. During the climb, the air traffic control system’s Short Term Conflict Alert (STCA) activated, when the aircraft were 10.1 NM horizontally and 200 ft vertically apart. The STCA alerted the controller to a pending breakdown of separation with the southbound aircraft, DINGO 008, maintaining FL270. The controller issued both flight crews with safety alerts and instructions that limited the severity of the separation breakdown. The aircraft passed 4.8 NM horizontally and 100 ft vertically of each other.

The controller had not identified the conflict before the STCA activation but their knowledge and application of effective compromised separation recovery techniques was integral to resolving the issue, following their recognition of the situation.

This incident highlights the importance for controllers to effectively balance their professional desire to promptly facilitate pilot requests with the overriding requirement to provide a safe and efficient air traffic control service.

The prompt and effective controller reaction to re-establish the appropriate separation standard highlights the benefit of and importance of regular compromised separation recovery training as an integral defence.

Aviation Short Investigation Bulletin - Issue 13