What happened
On Thursday, May 23, 1991, at 12:13 local time, a serious air traffic incident occurred within the Helsinki-Malmi terminal control area. A Boeing 72XXXXXXXXXXXXXXXX727-230, registration TC-RUT, operated by the Turkish airline Tur European Airways, deviated from its intended flight path. Instead of approaching Helsinki-Vantaa Airport, the aircraft flew over the taxiway of Helsinki-Malmi Airport, which was part of a former, decommissioned runway.
The incident was classified as a serious near-miss because the large commercial aircraft descended below prescribed approach altitudes while traversing the Malmi airspace, an area characterized by high traffic density. The flight path took the aircraft through a heavily populated region, significantly increasing the potential for widespread ground consequences had an accident occurred. There were no injuries and no damage to property or aircraft resulting from the event.
The investigation
Following the event, the Finnish authorities initiated an investigation into the near-miss. An investigation board was established by the Finnish Government on May 30, 1991, to determine the circumstances surrounding the deviation. The board's scope included examining the flight path and the low-altitude transit through the busy Malmi airspace.
The investigators conducted a comprehensive review, which included interviewing air traffic controllers, passengers on the aircraft, and the pilots of a military aircraft that was operating in the vicinity at the time. Additionally, eyewitnesses to the low-altitude flight were interviewed. To ensure a thorough technical review, two members of the investigation board traveled to Turkey to examine relevant operational details. The final draft of the report was shared with the Turkish civil aviation authorities for their comments, in accordance with ICAO Annex 13 protocols.