Flying for the Air Service provides a realistic picture of the typical flying experiences of the pilots who flew for the fledgling American Air Service during World War I. The narrative describes two brothers from Boston, George and Gerard Hughes, as they progress from apprentice pilots to flight instructors and combat pilots. After completing their pilot training program together, both were assigned as instructors.

Then George was sent to France with the 12th Aero Squadron, where he flew two-place observation aircraft over the front lines. Gerard, meanwhile, remained in America, instructing students in Texas. Eventually Gerard joined his brother's squadron in France as the war ended. Through the detailed letters and narrative comments of these two pilots, we can see clearly the hazards and challenges that were faced by those who flew in the early years of American aviation.