All information on this page is taken from the GPS Satellite Outage File and SEM
almanacs produced by the US Air Force
2nd Space Operations Squadron, who operates the GPS Constellation.
Historical outages are colored black,
Predicted outages are colored gold,
Current outages are colored red
A GPS historical outage table can be accessed from the link below. The historical
outages table contains all GPS outages since 1998.
The information below shows the number of healthy GPS satellites, since 1998. The
number of satellites in the GPS constellation comes from the SEM almanac for that
day. The number of unhealthy satellites for that day comes from the Satellite Outage
File. The SOF outages are subtracted from the number of satellites in the constellation
to get the number of healthy satellites.
The list of unused PRN numbers come from those PRNs not listed in the SEM almanac.
This graph plots the number of healthy GPS satellites since 1998 (Full History),
or over the last 365 days.
Note that since this is calculated on a daily boundary, this graph will show sequential
outages in a single day as concurrent, and may not reflect the more updated statistics