Jan. 4, 2017 JB Charleston tests new equipment, saves Air Force millions JOINT BASE CHARLESTON, S.C. -- An operational evaluation of new synthetic tiedowns and winch cables for the C-17 Globemaster III took place here Nov. 28 and 29, 2016. Tiedowns are ropes, cords, straps or chains that secure items during airlift operations. Winch cables help adjust the tension on