Handover at the End of a Night Shift
At 0550, a controller finishing a fifth consecutive night shift takes over a radar sector during a busy arrival bank. The outgoing controller gives a rapid verbal handover; the new controller misses that two aircraft with similar callsigns are at FL 190 and FL 200 on converging tracks. At 0605, the short-term conflict alert activates. The controller had slept 4 hours and skipped the last break. The sector is busy, and the third controller is on a phone call.
1. Identify the human factors at play and state your immediate actions after the STCA activates.
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The main threats are fatigue from a fifth consecutive night shift and four hours' sleep, a rushed and unstructured handover, similar callsigns, high workload and distraction because the third controller is on the phone. The STCA is the last barrier. Immediately issue avoiding instructions to both aircraft, using full callsigns to prevent a similar-callsign error: for example, 'ABC123, turn right heading 090, descend FL 180' and 'ABD123, turn left heading 270, maintain FL 200.' Confirm each readback individually, then re-establish the required separation and check for other conflicts in the sector.
2. What should have been done at the handover to reduce the risk?
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The handover should have been structured and confirmed, not a rapid verbal dump. The outgoing controller should have identified the two similar callsigns, their levels and converging tracks, and the new controller should have read back the key points. A written or electronic strip display should have been checked, and the handover should have included known conflicts, traffic in the arrival bank and any outstanding coordination. If fatigue was evident, the supervisor should have been told before the position was accepted, and a short break or a second pair of eyes should have been arranged.
3. How should the event be reported, and what just-culture and SMS lessons apply?
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The STCA activation and the loss of separation should be reported through the occurrence-reporting system and to the supervisor, with voice and radar recordings preserved. The investigation should focus on the fatigue roster, the handover procedure, similar-callsign handling, staffing during the arrival bank and the phone distraction. A just culture does not ignore the error, but it distinguishes systemic precursors from reckless conduct. Corrective actions could include a fatigue risk management review, a standard handover checklist, callsign-confusion alerts and a rule that phone calls do not remove a controller from a safety-critical role without relief.