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.
GPS satellite outages identified as current by the US Air Force. Current outage types are usually reserved for unscheduled outages.
|18||34||2018012.5||UNUSUFN||Mar 13, 2018 18:31:00|
GPS satellite outages identified as predicted by the US Air Force.
There are no predicted outages at this time.
GPS satellite outages identified as historical by the US Air Force, occurring within the last month.
|PRN||SVN||NANU||Type||Outage start||Outage stop||Duration|
|11||46||2018007||FCSTSUMM||Mar 01, 2018 14:31:00||Mar 01, 2018 21:00:00||00d:06h:29m:000s|
|18||54||2018009||UNUSABLE||Jan 23, 2018 16:50:00||Mar 05, 2018 22:00:00||41d:05h:10m:000s|
|20||51||2018012||FCSTSUMM||Mar 08, 2018 23:21:00||Mar 09, 2018 06:15:00||00d:06h:54m:000s|
|3||69||2018013||FCSTSUMM||Mar 15, 2018 13:55:00||Mar 15, 2018 19:31:00||00d:05h:36m:000s|
|30||64||2018014||UNUNOREF||Mar 20, 2018 10:50:00||Mar 20, 2018 10:52:00||00d:00h:02m:000s|
Last checked for outage data: 2018-03-21 10:57:17Z
GPS outages in a calendar format from AGI can be found here:
Historical GPS Outages can be found here:
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.
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.