C10a/2002L Loss of Separation East of Turku Airport on 23.10.2002

On Wednesday, October 23, 2002, at 14.10.35 UTC an incident took place east of Turku Airport, on runway 08 extension at an altitude of 4200 ft above sea level when a Gulfstream G100 (HB-VNF), a corporate aircraft on a non-commercial flight from Turku to Bern, during climb passed through the altitude of an ATR-72-201 (FIN229) on a scheduled flight, operated by Finnair Oyj, at a horizontal distance of about 1.8 NM. The aircraft were on IFR flights under visual meteorological conditions. The Accident Investigation Board Finland appointed an investigation commission on November 11, 2002, to investigate the incident. Airline transport pilot Jussi Haila was appointed chairman of the commission and air traffic controller Erkki Lepola and MSc Ville Hämäläinen were appointed members of the commission.

HB-VNF received takeoff clearance from runway 08 at Turku Airport with initial climb restriction 3200 ft on the altimeter setting of QNH 1003. HB-VNF was cleared to continue climb after established radial 236 from Turku VOR/DME RUSKO via right turn. At the same time FIN229, approaching the left down-wind leg of runway 08 from east, followed its clearance to descend to 4200 ft on QNH. HB-VNF did not comply with its initial climb restriction, but continued the climb passing through the FIN229 altitude of 4200 ft. At the passing-through time the horizontal distance between the two aircraft was about 1.8 NM, and HB-VNF had initiated its right turn. The pilots of both aircraft saw the other aircraft on their TCAS displays. The pilots of FIN229 also obtained visual contact to HB-VNF.

The investigation indicated that the pilots of HB-VNF had not understood the initial climb restriction of 3200 ft in their clearance, but continued their climb and passed through the altitude of FIN229 approaching Turku resulting in a loss of required separation between the two aircraft. According to the commander’s statement, they had understood that they had to climb on runway heading to 3200 ft and turn on course thereafter. The first officer had, however, correctly read back the air traffic control clearance. A contributing factor to the incident was that FIN229 flying in accordance with its visual approach clearance was not given any traffic information. Traffic information is not required for two separated aircraft, but in the investigation commission’s opinion the traffic information would have implied provision of good air traffic service in this case.

The investigation commission recommended that the Finnish Civil Aviation Administration together with Turku Airport would develop and apply standard instrument departure and arrival routes with mandatory separation between them at Turku Airport. Such standard instrument departure routes would better outline the traffic and improve its control. The pilots of aircraft equipped with modern cockpit technology would benefit more from their cockpit equipment if assisted by standard instrument routes.

C10a/2002L Report (pdf, 0.15 Mt)