At 15:36 Greenwich Mean Time yesterday, GPS satellite SVN 23/PRN 32, the oldest satellite in the GPS constellation, became unusable. It was taken out of service at 22:00 GMT. See Notice.

Although this was supposed to have been a routine decommissioning, reports from industry indicate some GPS receivers immediately began to malfunction.

Impacts to receivers varied by type and manufacturer. Receiver models from at least eight different manufacturers failed while other models and the products of other manufacturers were not impacted at all. For timing receivers that failed, cesium and rubidium backup clocks seem to have provided sufficient hold over for most until technicians could respond.

Reports from Europe indicate that systems at at least nine major corporations were impacted.  Some of those companies provide critical national infrastructure.

Perhaps most concerning is that as of this writing, 18 hours after the onset of the problem, some receivers are still not able to reacquire time or location using the other 30 good satellites.

On a phone call with the Air Force GPS Operations Center we were told there was a “software problem” associated with the decommissioning. This software problem was fixed at 11:17 GMT today (26 Jan 16), we were told.

According to the Air Force, some receivers may need to be rebooted, but all should work normally thereafter.  The Air Force promises a message describing the incident for the public.