Josef František was a Czechoslovak fighter pilot and Second World War fighter ace who flew for the air forces of Czechoslovakia, Poland, France, and the United Kingdom. He was the highest-scoring non-British Allied ace in the Battle of Britain, with 17 confirmed victories and one probable, all gained in a period of four weeks in September 1940.

The Czechoslovak Air Force or the Czechoslovak Army Air Force was the air force branch of the Czechoslovak Army formed in October 1918. The armed forces of Czechoslovakia ceased to exist on 31 December 1992. By the end of the year, all aircraft of the Czechoslovak Air Force were divided between the Czech Air Force and the Slovak Air Force.