Background
On Thursday, 23 November 2017, an Airbus A320-200, registration VP-BWI, call sign SDM-6641, operated by airline "Russia", was conducting a scheduled flight from Sankt-Petersburg/Pulkovo (ULLI) to Berlin-Schonefeld (EDDB). The aircraft was at flight level (FL) 360 in Latvia airspace.
At the same time, two F-15C aircraft, call signs MA01 and MA02, were tasked by the Combined Air Operations Centre (CAOC) at Uedem, Germany, with an Alpha Scramble (A-SCR) mission to intercept targets transiting over international waters with transponders switched off. The F-15Cs departed from Šiauliai (EYSA) at 07:45 UTC. Their mission was controlled by the Mission Control Unit (MCU) Control Reporting Centre "KARMELAVA" in Lithuania, with a Fighter Controller (FC) and Fighter Allocator (FA). Coordination was made with appropriate Air Traffic Service (ATS) units in Vilnius and Riga.
Sequence of Events
At 07:41:54, Vilnius ATC informed the Riga Sector West Controller about three operational traffic aircraft from Kaliningrad at FL 350 and FL 360 with no communication. At 07:42:24, the MCU FA contacted the Operational Supervisor (OSUP) and announced an Alpha Scramble likely entering Riga airspace. The initial cleared flight level for the F-15Cs was FL 250, with reduced separation of 1,000 feet below FL 290 agreed upon.
At 07:52:42, the FA requested FL 330 and above FL 300 for supersonic flight. The OSUP granted clearance to climb to FL 340 and go supersonic, with 2,000 feet separation. The FC cleared the F-15Cs to FL 340, which was acknowledged by the pilot at 07:53.
At 07:51:34, the A320 pilot contacted the West Controller, reporting at FL 360. At 07:54:09, the controller called the A320 and at 07:54:15 informed: "Russia 6641, be advised, military traffic 2000 feet below you about to go supersonic." Immediately after, at 07:54:23, the A320 crew reported a TCAS Resolution Advisory (RA).
Despite the instruction from the FC to stop at FL 340, the military aircraft violated the cleared level, triggering the TCAS RA. The crew of the A320, with SSR code 3725, followed the TCAS instructions.
Separation Details
The incident occurred in the Riga FIR Class C airspace, within a Terminal Control Area (TMA). The minimum horizontal separation recorded was 3.6 nautical miles, and the minimum vertical separation was 200 feet.
Classification
The Transport Accident Investigation Bureau (TAIIB) classified the occurrence as a serious incident and initiated an investigation under Annex 13 to the Chicago Convention and EU Regulation No 996/2010.