C6/2003L Loss of separation minima in Kuopio Terminal Area on 29 April 2003

On Tuesday 29 April 2003 at 10.42 local time there was an aircraft incident on Kuopio Terminal Area in which the separation was lost. The accident Investigation Board Finland decided to set up a commission to investigate the incident on 7 June 2003. Investigator Erkki Rissanen was appointed as investigator-in-charge and investigator Pekka Alaraudanjoki as member of the commission.

Finnish Air Force Hawk-couple, call sign J11, had been cleared for take-off on runway 15 which was the runway in use. The clearance of the couple was to turn left towards north-east after takeoff and to maintain 550 metres on QFE until the training area. At the same time ATR-72-201 aircraft, call sign FIN503, owned and operated by Finnair Oyj, on a scheduled passenger flight from Helsinki, approached Kuopio airport from South. FIN503 had asked to use runway 33 if possible in respect to other traffic. The radar controller decided to use runway 33 for landing for FIN503. He vectored the aircraft to the left base leg of runway 33 at about 14 km from the runway threshold. He also cleared it to descend to 2100 feet on QNH 1004 hPa which was the same altitude as 550 m on QFE 993 hPa where the departing Hawk-couple had been cleared. J11-couple took off one by one with 20 second intervals towards the FIN503. J11 did not have enough time to turn away from the final approach line of runway 33 before the separation to FIN503 was lost.

The approach controller noted on his radar screen that J11 continues on the runway 15 heading longer than he had expected and the separation to FIN503 was about to be lost. He ordered the descending FIN503 to maintain 3100 feet, to make an orbit to right and then to fly heading 330. J11 turned left towards north-east and the controller ordered it to continue towards the training area maintaining 550 metres. J12 lost visual contact to the J11 and the controller ordered it to turn right heading 220, to maintain 550 metres and to switch on the transponder.

FIN503 had received a TCAS (Traffic alert and Collision Avoidance System) Traffic Advisory according which the other aircraft was about 500 feet below. The pilots did not get visual contact with the other aircraft. The separation between FIN503 and J11 was lost approximately 8 seconds. The smallest horizontal distance between the aircraft was 4.6 km and smallest vertical distance 180 metres when the separation was lost. The separation between FIN503 and J12 was maintained all the time.

The cause of the incident was the fact that the approach controller abandoned the vertical separation between FIN503 and J11 without securing the horizontal separation.

C6/2003L Report (pdf, 0.5 Mt)