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GPS Satellite Outages

GPS satellite outages are determined by the US Air Force using a Notice Advisory to Navstar Users (NANU). NANUs are categorized by their type and can represent forecasted, current or summary outages. See the full list of outage types on the CelesTrak website.


Current Time


Current Outages

GPS satellite outages identified as current by the US Air Force. Current outage types are usually reserved for unscheduled outages.

PRNSVNNANUTypeOutage start
23762020033UNUSUFNJun 30, 2020 20:10:00

Predicted Outages

GPS satellite outages identified as predicted by the US Air Force.

NOTE: The satellite outage file supplied by 2SOPS and made available to the public on the NAVCEN website has errors

  • SVN34/PRN18 was reported as unavailable to users 7 Oct 2019. The PRN was given to SVN75 at launch on 12 Mar 2020 per NANU 2020011, but no DECOM was issued. As a result, the SOF currently reports a PREDICTED outage for SVN34/PRN18 which is incorrect since the satellite is no longer in the almanac.
  • SVN60/PRN23 was reported as unavailable to users 9 Mar 2020. The satellite was decommissioned on 9 Mar 20 per NANU 2020010, but the SOF was not updated. As a result, the SOF currently reports a PREDICTED outage for SVN60/PRN23 which is incorrect since the satellite is no longer in the almanac.
  • SVN41/PRN14 was reported as unavailable to users 9 Jul 2020. The satellite was decommissioned on 9 Jul 20 per NANU 2020034, but the SOF was not updated. As a result, the SOF currently reports a PREDICTED outage for SVN41/PRN14 which is incorrect since the satellite is no longer in the almanac.
PRNSVNNANUTypeOutage startOutage stopDuration
18342019156FCSTUUFNOct 07, 2019 20:00:00Dec 31, 9999 23:59:59Infinity
23602020010FCSTUUFNMar 09, 2020 15:30:00Dec 31, 9999 23:59:59Infinity
14412020031FCSTUUFNJul 09, 2020 18:00:00Dec 31, 9999 23:59:59Infinity
25622020045FCSTMXOct 01, 2020 19:00:00Oct 03, 2020 19:00:0002d:00h:00m:000s

Recent Outages

GPS satellite outages identified as historical by the US Air Force, occurring within the last month.

PRNSVNNANUTypeOutage startOutage stopDuration
4742020043UNUSABLESep 20, 2020 00:31:00Sep 20, 2020 05:47:0000d:05h:16m:000s
32702020044FCSTSUMMSep 22, 2020 21:36:00Sep 23, 2020 02:35:0000d:04h:59m:000s

Last checked for outage data: 2020-10-01 03:14:27Z


Other links

GPS outages in a calendar format from AGI can be found here:

GPS Satellite Outage Calendar

Historical GPS Outages can be found here:

Historical GPS Satellite Outages


Navigation blog entries

Gps Basics
The basics of how GPS works with some technical content.

How Long Can You Use an Almanac?
GPS position data is contained in almanac files. Learn how long you can use these for analysis.


Selection of my published papers

Operational Considerations for Improved Accuracy with an IOC Galileo Constellation
This paper looks at how the Galileo operators can improve the performance of an initial Galileo constellation by managing their ephemeris and clock errors. Keeping those errors small can help keep initial positioning errors small, even when large DOPs are present.

Long term prediction of GPS accuracy - Understanding the Fundamentals
Topics on prediction methods for GPS and how long GPS errors can be predicted. Starting from an understanding of the elements of prediction, including almanac use and ephemeris and clock errors, I look at the statistics of GPS position error predictions under various scenarios.

Statistical Analysis of Military and Civilian Navigation Error Data Services
This paper examines the difference between ephemeris and clock errors generated using civilian data versus those generated using military data. The different data sources result from civilian GPS receiver and military GPS receiver.