What happened
On November 24, 2010, at approximately 08:00 UTC, a separation minima violation occurred approximately 30 NM north of Helsinki. The incident involved an Avro RJ85, registration OH-SAL, operating a scheduled flight from Oulu to Helsinki-Vantaa, and a Cirrus SR2 2, registration OH-GSB, conducting a training flight from Helsinki-Malmi to Jyväskylä. Both aircraft were flying under instrument flight rules (IFR) and were approaching each other from nearly opposite directions.
During the flight, the OH-SAL experienced a fuel pump failure, prompting the crew to request a direct routing to the PODOM intermediate approach fix and a descent to FL100 to expedite arrival. Simultaneously, the OH-GSB was cruising at FL100. Due to the simultaneous operation of both aircraft at the same altitude on intersecting paths, a conflict developed. Although air traffic controllers initiated separation maneuvers, the aircraft passed within approximately 2.7 NM of each other with a vertical separation of only about 400 feet, failing to maintain the required 3 NM lateral or 1,000-foot vertical separation minima.
The investigation
The investigation examined the operational environment and technical status of the air traffic control systems. It was established that the Area Control Centre (ACC) was experiencing a significant failure of its Eurocat 2000 radar display system and Flight Data Processing System (FDPS). This failure prevented the automatic processing of flight plans and meant that the OH-GSB was not visible on the ACC radar displays. Consequently, coordination between the ACC and Helsinki Approach had to be conducted via telephone rather than through automated systems.
The investigation also looked into the communication between the crews and controllers. It was noted that the OH-SAL crew used non-standard phraseology when reporting their new altitude, which may have caused ambiguity regarding their flight level. While the OH-SAL's TCAS provided a Traffic Advisory (TA), the OH-GSB was not equipped with TCAS, and the heavy cloud cover prevented visual acquisition of the other aircraft.
Findings
- The primary cause of the separation breach was inadequate coordination between air traffic control units and workstations during an abnormal operational situation.
- A significant contributing factor was the increased workload imposed on controllers due to the failure of the Eurocat 2000 radar display system and the FDPS at the Area Control Centre.
- The failure of the FDPS meant that the OH-GSB lacked identification labels on the ACC radar, complicating traffic management.
- The use of non-standard phraseology by the OH-SAL crew regarding their descent and altitude contributed to potential ambiguity in separation responsibilities.