Captains of the Clouds (1942) with Cagney, among others.
Bush pilots in northern Ontario compete for jobs and women in the 1930s. Then they step forward and volunteer during WW2.
I thought this was a really good film--has some of the melodrama you see in older movies, but it also has great character development, which is rare in newer movies.
Billy Bishop has a role in this flick as well.
WW