On 28 January the US Air Force announced from the 2nd Space Operations Squadron at the 50th Space Wing, Schriever Air Force Base, Colorado, that verified users were experiencing GPS timing issues.
Further investigation revealed an issue in the Global Positioning System ground software which 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 0610 MST, however global users may have experienced GPS timing issues for several hours.