Maintainers assigned to the 20th Aircraft Maintanence Squadron, Shaw Air Force Base, S.C., perform a caliber test on an F-16 Fighting Falcon during Red Flag 15-4 at Nellis AFB, Nev., Aug. 19, 2015. Maintainers are responsible for overseeing the day-to-day maintenance of aircraft, including diagnosing malfunctions and replacing components, and conducting various inspections to ensure the aircraft is functioning properly. (U.S. Air Force photo by Airman 1st Class Mikaley Towle)