“Airman” means any individual who engages, as the person in command, or as pilot, mechanic, or member of the crew, in the navigation of aircraft while under way, and any individual who is directly in charge of the inspection, maintenance, overhauling, or repair of aircraft engines, propellers, or appliances, and any individual who serves in the capacity of aircraft dispatcher, or air traffic control-tower operator. “Airman” does not include any individual employed outside the United States, or any individual employed by a manufacturer of aircraft, aircraft engines, propellers, or appliances to perform duties as inspector or mechanic in connection therewith, or any individual performing inspection or mechanical duties in connection with aircraft owned or operated by him.