U.S. Air Force Airman 1st Class Avery Fortenbery, a 13th Aircraft Maintenance Unit crew chief, installs the lower pin on an F-16 Fighting Falcon at Misawa Air Base, Japan, Dec. 11, 2018. The aircraft-safe maintenance procedures communicate to the rest of the crew the aircraft is cleared to have post-flight maintenance work performed on it. (U.S. Air Force photo by Airman 1st Class Genesis Tejada)