Air Force determines cause of GPS timing issue

On Jan. 26 at 12:49 a.m. MST, the 2nd Space Operations Squadron (2 SOPS) at the 50th Space Wing, Schriever Air Force Base, Colo., verified users were experiencing GPS timing issues. Further investigation revealed an issue in the GPS ground software that only affected the time on legacy L-band signals. This change occurred when the oldest vehicle, SVN 23, was removed from the constellation.

While the core navigation systems were working normally, the coordinated universal time timing signal was off by 13 microseconds, which exceeded the design specifications. The issue was resolved at 6:10 a.m. MST; however, global users may have experienced GPS timing issues for several hours.

U.S. Strategic Command’s Commercial Integration Cell, operating out of the Joint Space Operations Center, effectively served as the portal to determine the scope of commercial user impacts. Additionally, the Joint Space Operations Center at Vandenberg AFB has not received any reports of issues with GPS-aided munitions, and has determined that the timing error is not attributable to any type of outside interference such as jamming or spoofing.

Operator procedures were modified to preclude a repeat of this issue until the ground system software is corrected, and the 50th Space Wing will conduct an Operational Review Board to review procedures and impacts on users. Commercial and Civil users who experienced impacts can contact the U.S. Coast Guard Navigation Center at (703) 313-5900.