On 26 January at 12:49 a.m. MST, the 2nd Space Operations
Squadron at the 50th Space Wing, Schriever Air Force Base, Colo., 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 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.
V/R
Rick Hamilton
CGSIC Executive Secretariat
GPS Information Analysis Team Lead
U.S. Coast Guard Navigation Center
703-313-5930
