A trio of wartime pilots are working on the US Mail routes, flying in all weathers trying to keep the post moving across a nation where the weather can change with little, or no, notice. “Jake” (Pat O’Brien) leads the gang, “Tex” (Stuart Erwin) is the dependable type and the pencil-moustachioed “Dizzy” (James Cagney) is a bit of a loose cannon. It’…