[Swedish] count [Eric von Rosen] used the swastika as a personal good luck charm. When he gifted a plane to the nascent air force of Sweden’s newly independent neighbour in 1918 he had had a blue swastika painted on it. This Thulin Typ D was the first aircraft of the Finnish air force and subsequent planes all had his blue swastika symbol too, until 1945.

Supporters of a continued use of the symbol point out that there were no Nazis in 1918 so the air force’s use of the swastika has nothing to do with Nazism.

However, while Eric von Rosen had no Nazi associations at the time of his 1918 gift, he did subsequently become a leading figure in Sweden’s own national socialist movement in the 1930s. He was also a brother-in-law of senior German Nazi Herman Göring, and, according to Prof Teivainen, a personal friend of Hitler.

So the fascists adopted the swastika by way of a Swedish Count-cum-fascist.

Also: https://en.wikipedia.org/wiki/Air_Force_Academy_(Finland)