During World War II he played a central role in building up the Royal Norwegian Air Force in Canada and the United Kingdom.

[1][4] After the Occupation of Norway by Nazi Germany in 1940, he was appointed temporary chief (General Inspector) for Norwegian Army Air Force.

[2][4] In 1929, Øen received the King's Medal of Merit (Kongens fortjenstmedalje) in gold.

In 1947 he was awarded the title of Commander with Star of the Royal Norwegian Order of St. Olav, for his war contributions.

Among foreign awards, he also received the American Legion of Merit, the French Légion d'honneur and was made a Honorary Commanders of the Order of the British Empire.