What happened
On June 11, 2007, at 15:17 UTC, a Ryanair Boeing 73 and 800, operating flight RYR8403 from London Stansted to Brno-Tuřany, experienced a serious near-collision incident within the Brno TMA. While being vectored for an ILS approach to runway 28 at flight level 61, the flight crew observed a glider performing a steep right-hand turn in close proximity to their aircraft.
The pilot in command (PIC) identified the conflicting VFR traffic and alerted the first officer. The PIC noted that the glider's maneuver appeared to clear the path, allowing the crew to continue their descent. The aircraft subsequently passed the glider with a separation of approximately 150 ft at roughly the same flight level. Following the encounter, the crew reported the "glider activity" to Brno Approach (APP EC).
The investigation
The ÚZPLN investigation analyzed radar records from the Brno ATS station, including both passive and active modes, to reconstruct the flight trajectories. The investigation established that the glider, a LAK 17 with registration OK-1507, had entered the Brno TMA without establishing communication or obtaining flight clearance.
Radar analysis confirmed that the unidentified target followed a path from the vicinity of Račice toward the northern edge of the Tuřary CTR. While the air traffic controller (APP EC) was managing multiple primary radar targets, the lack of an SSR transponder on the glider made it extremely difficult to distinguish the unauthorized entry from other stationary or moving primary targets. The controller only identified the glider as a potential conflict after the Ryanair crew reported the encounter and the Tower controller noted a primary radar target near the Boeing's position.
Findings
- The primary cause of the incident was the unauthorized entry of the glider into the controlled airspace without prior clearance or communication with ATC.
- The pilot of the LAK 17 entered the TMA without establishing contact with Brno Approach.
- The glider was not equipped with an SSR transponder, which hindered the controller's ability to identify and track the aircraft effectively.
- The Ryanair crew acted correctly by identifying the conflict and notifying ATC immediately.
- The air traffic controller was unable to detect the unauthorized entry due to the difficulty of identifying a non-transponding target among other primary radar returns in the area.