Pursuant to the 6-hour Galileo system outage on December 14, the European GNSS Agency (GSA) issued an update stating that the “service incident,” while still under investigation, “is confirmed to be related to an abnormal behaviour of a ground atomic clock in the time determination function of the system.” Galileo FNAV December 14 outage The statement continues “The time synchronisation and orbit determination algorithms immediately flagged the data as MARGINAL (SISA*=NAPA**) before it affected the quality of the measurements. However, the incorrect data was still uploaded to the satellites. User receivers that do not process the health and status flags, or that keep MARGINAL satellites as part of the position solution computation, may have experienced large positioning errors.”