What happened
On August 16, 1999, at approximately 15:14, a near-collision occurred on the final approach to runway 34 at Vaasa Airport. The incident involved a Finnish Air Force Vinka VN-21 training aircraft, operating under the callsign M 42, and a Skyways AB Fokker 50, registration SE-LIN, performing a scheduled passenger flight (SKX 1593).
The air traffic controller was managing a mix of VFR and IFR traffic. The Fokker 50 was on a visual approach to runway 34. Simultaneously, the Vinka training aircraft was cleared for a through landing. During the sequence, the controller instructed the Vinka to perform a left-hand circuit to allow the larger aircraft to land. However, the Vinka pilot initiated a left turn before the specific instruction was issued. The controller, while managing the arrival of the Fokker 50, cleared the Vinka for a through landing without verifying the exact positions of both aircraft.
The investigation
The investigation examined the air traffic controller's actions, the movement of both aircraft, and the working conditions at Vaasa Tower. Investigators reviewed radio communications, radar monitor data, and the controller's duty logs. The investigation also looked into the controller's fatigue levels, noting that the controller had completed an evening shift the previous night and had only ten hours of rest before starting the current shift.
Findings
- The primary cause of the near-collision was that the air traffic controller cleared the Vinka for a through landing without verifying the position of either approaching aircraft.
- The controller failed to issue traffic information to either aircraft during the approach phase.
- The controller did not utilize the available radar monitor to assist in aircraft positioning.
- The controller was likely working at a computer terminal with their back to the traffic during the critical moments of the approach.
- The controller's rest period was insufficient, as they had only ten hours of rest between shifts.
- The controller did not request position or distance reports from either aircraft during their arrival or approach.