Introduction
On 8 September 2016 at 15:03 UTC, a serious incident involving a loss of separation occurred in the controlled airspace of the Republic of Bulgaria. The incident involved an Airbus A321-211 aircraft, registration TC-ATF (call sign KKK8JY), operated by Atlasjet, and a Boeing B737-8F2 aircraft, registration TC-JVS (call sign THY4AV), operated by Turkish Airlines. The occurrence was classified as a serious incident by the Bulgarian Aircraft Accident Investigation Unit (AAIU) under the provisions of ICAO Annex 13, EU Regulation 996/2010, and Bulgarian Ordinance 13.
Aircraft Information
The Airbus A321-211 (manufacturer serial number not specified) with registration TC-ATF was operated by Atlasjet. The Boeing B737-8F2 with registration TC-JVS was operated by Turkish Airlines. Both aircraft were conducting instrument flight rules (IFR) operations. The flight crew details are provided in the report but are not elaborated in the source text.
Investigation Process
The investigation was notified to multiple international bodies, including the European Commission, ICAO, the French BEA, EASA, the Turkish investigation board (Maritime Affairs and Communications Accident Investigation Board), and the US NTSB. The case was filed under number 06/08.09.2016. The objective of the investigation was to establish the causes of the loss of separation without apportioning blame or liability.
Report Structure and Content
The final report includes sections on factual information, such as flight history, personnel information, aircraft systems, meteorological conditions, communications, flight data recorders, and additional technical details like activated warning systems (Short-Term Conflict Alert and Airborne Collision Avoidance System) and autopilot/flight director modes. The analysis and conclusion sections provide findings and causes, but the specific text of the causes is not available in the provided source. Safety recommendations are also included in the report but are not detailed here.
Conclusion
The report identifies causes for the serious incident, but the explicit statement of probable cause is not present in the source text. Therefore, no probable cause is declared.