The brother-in-law of an RAF messenger finds an addressed letter in the pocket of his uniform after the brother-in-law has changed clothes at home and left on a three-day pass to visit his mother. Thinking that his sister's husband forgot to deliver the important message, George Brown decides to deliver it for him. So, he dons the other's uniform and takes off, posing as his brother-in-law. But, once on the base, he's caught in a series of orders and assignments that lead to pandemonium.
It's a funny tale with Formby playing his ukulele, being the butt of pranks by a Corporal Craig, and his befuddling the Sergeant Major. But the pranks by Craig backfire as the top dog's daughter, Peggy, falls for George and leaves Craig in the lurch. It all ends with some crazy flying scenes that are a mix of models and real flying in a biplane with Brown at the controls and Craig as his radio operator.
This 1938 British film by Associated Talking Pictures was titled "It's in the Air" in the U. K. It was renamed for U. S. release as "George Takes the Air." That was most likely to distinguish it from a 1935 Jack Benny comedy film, "It's in the Air."