The two worst air accidents in Finland have been Koivulahti 1961 and Maarianhamina in 1963. In both cases it was Douglas DC-3 (actually converted C-47) involved.

The post-WWII years in the Finnish civilian aviation were rather wild. Aero OY, the Finnish national airlines (today's Finnair) had expanded rapidly, and many WWII aviators had found a new career in the commercial aviation. Aviators, who had gotten used to take insane risks in the war, also took insane risks in the peacetime. The Finnish pilots considered it as an honour to fly in weather where nobody else would fly.

In Koivulahti 3 Jan 1961, the pilot Lars Hattinen, a six-victory WWII ace, flew in bad weather heavily intoxicated by alcohol, and he stalled on a turn on approach to Vaasa, with the DC-3 spinning in the ground. This combination - bad weather, flying under influence and the wingtip stalling tendency of DC-3 - made him to take risk which might have succeeded in good weather, but was fatal. 25 people died in the accident.

Two years later, the Aero OY DC-3 flew into ground (CFIT or Controlled Flight into Terrain) at the approach of Mariehamn airport 8 Nov 1963 in bad weather and dense fog. This time the culprit was faulty altimeter, which displayed 50 feet too much. It would not mattered at VFR conditions, but was fatal in bad weather. Of the 25 people on board, 22 perished.

Aero OY tightened its flying rules and standards as result. Today Finnair is one of the safest airlines in the world.

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