What happened
On December 13, 2006, a separation minima infringement occurred in the Prague FIR near VOR BNO. The incident involved a commercial Canadair CRJ2 (callsign MAH541) operating a scheduled flight from Hamburg to Budapest and a military L-1s9 (callsign 2507) operated by the Czech Air Force.
At approximately 09:40 UTC, the Canadair CRJ2 checked in with the Prague Area Control Center (NEM EC) at flight level 310. Shortly thereafter, the pilot of the L-159 checked in with the military Area Control Center (EC MACC) and was instructed to climb to flight level 300.
During the coordination process, the military procedural controller (PC MACC) verified the flight plan for MAH541 with the civil controller (PC ACC). At 10:00 UTC, the civil controller inquired whether the military aircraft was equipped for RVSM (Reduced Vertical Separation Minimum) operations. The military controller informed the civil controller that the L-159 was not RVSM-equipped. Consequently, the civil controller alerted the military controller to the need for increased separation.
The investigation
The ÚZPLN investigation focused on the activities of the military Area Control Center (EC MACC) regarding the management of the military flight within RVSM airspace. The investigation utilized radar records and radio/telephone communications between the crews and air traffic services to reconstruct the sequence of events.
Findings
- The investigation established that the vertical separation between the two aircraft was reduced to 1000 ft, whereas regulations required a minimum of 2000 ft because the military aircraft was not RVSM-equipped.
- The primary cause was that the EC MACC controller failed to account for the fact that the L-159 was not equipped for RVSM operations when issuing the climb clearance to flight level 300.
- The incident was the result of incorrect procedures by both the EC MACC and PC MACC controllers, who failed to ensure the required vertical separation was maintained.