Tech. Sgt. Andrew Gravett walks along the top of a C-17 Globemaster III while wearing a safety harness as he does a routine maintenance check of the aircraft June 4, 2013, at Joint Base Charleston, S.C. The first C-17 to enter the Air Force's inventory arrived at Charleston Air Force Base in June 1993. The C-17 is capable of rapid strategic delivery of troops and all types of cargo to main operating bases or directly to forward bases in the deployment area. Gravett is a crew chief assigned to the 437th Aircraft Maintenance Squadron.