Staff Sgt. Barbara Bozeman, U.S. Air Force, demonstrates the operational check she performed on the hand-held Global Positioning System (GPS) units used by her squadron at Osan Air Base, South Korea, on Aug. 24, 1999. At midnight between Aug. 21 and 22 the clocks aboard all 24 GPS satellites automatically reset themselves to zero. The clocks count to 1,023 weeks before resetting to conserve memory space. The effects of the clocks resetting were not anticipated by all manufactures of equipment that utilizes the GPS satellites as a navigational reference point, date, and time. The GPS units are used to supplement the navigational equipment in the survival vests worn by the fighter pilots of the 25th Fighter Squadron. Bozeman, from Middletown, R. I., is the assistant non-commissioned officer in charge of Life Support for the 25th.