What happened
On October 31, 2002, at 16:37 local time, a serious loss of separation occurred approximately 43 km west-south-west of Turku Airport. An Air Botnia Oy Avro RJ85, registration OH-SAI, was operating a scheduled flight from Copenhagen to Turku. Simultaneously, a European Executive Express Jetstream 32, registration SE-LNV, was flying a scheduled route from Turku to Mariehamn.
The two aircraft were flying in opposite directions at approximately 2,500 m altitude. The Jetstream 32 was cleared to flight level 80, while the Avro RJ85 was cleared to descend through that level to 3,200 feet. The aircraft passed each other with a minimum vertical separation of only 500 feet, violating required separation standards. The collision was avoided only because the pilots of OH-SAI observed the opposing traffic on their TCAS display and aborted their descent, climbing back to flight level 90 before the aircraft passed.
The investigation
The investigation established that at the time of the incident, the air traffic control position was being managed by an air traffic controller student from Avia College. The active air traffic controller had moved approximately 2–3 meters away from the workstation and was dictating clearances to the student, who then relayed them via radio.
The investigation found that the controller had forgotten about the departing SE-LNV and issued a clearance to OH-SAI that directed it to descend through the altitude occupied by the other aircraft. The controller did not realize the error until the pilots of OH-SAI queried the opposing traffic following a TCAS alert. Furthermore, the controller was relying on memory and radio transmissions rather than utilizing flight strip markings or the radar monitor.
Findings
- The primary cause of the incident was that the air traffic controller delegated the workstation to a student who did not yet possess the necessary training to manage the traffic independently.
- The controller failed to utilize available traffic information, such as the radar monitor and flight strip markings, instead relying on memory and overheard radio traffic.
- The controller had forgotten the presence of the departing SE-LNV when issuing the descent clearance to OH-SAI.
- The student was not permitted by educational guidelines to handle the workstation independently at that stage of training.
- The radar monitor at the Turku workstation was poorly positioned and too small to be effectively used for monitoring the training session.
- There was a lack of formal on-the-job training guidelines and designated trainers at the Turku airport facility.