Background
On an unspecified date, two aircraft, callsigns SXS2Y and THY7NL, were operating in the Skopje Flight Information Region (FIR). The incident occurred during a critical period when separation minima were not maintained.
Events
The flight history, as recorded by radio communications and radar data, shows that SXS2Y and THY7NL converged. The Short Term Conflict Alert (STCA) activated, and the Traffic Collision Avoidance System (TCAS) issued Resolution Advisories (RAs) to both aircraft. The closest point of approach was less than the required separation.
Findings
The investigation identified several findings:
- Separation in terms of flight direction was inadequate.
- Direct routing approval to points outside the Skopje FIR was given without proper coordination.
- Communication and phraseology deviations occurred.
- Coordination with adjacent sectors was insufficient.
- Meteorological data collection and distribution had deficiencies.
- Safety reporting procedures were not followed.
- Cockpit technology, including TCAS, functioned as designed.
- The final report of a previous related event (A-030) contained factual errors.
- Sector splitting during the critical period affected workload.
- The turn speed of THY7NL toward point DIGTI was not controlled.
Direct Cause
The direct cause of the event was the air traffic controller's failure to maintain the required separation between SXS2Y and THY7NL, stemming from an inadequate assessment of the traffic situation and poor coordination.
Indirect Causes
Indirect causes included deficiencies in controller training, sector management, and communication procedures, as well as systemic issues in safety reporting and meteorological data handling.
Recommendations
The investigation issued safety recommendations aimed at improving controller training, revising procedures for direct routing approvals, enhancing coordination between sectors, and strengthening the safety reporting system.