Navigation Systems

6/20/2018: GPS satellite maintenance

The Navigation Center posted a notice to its website alerting users of the Global Positioning System (GPS) that there may be a short period of high Horizontal Dilution of Precision (HDOP) / Position Dilution of Precision (PDOP) in the locations below at the times indicated due to satellite maintenance (please refer to NANU 2018029, available on our Constellation Status Page). High Dilution of Precision is defined as HDOP in excess of 6.

  • In the vicinity of 62.00N, 40.00E, between Mastalyga and Shozhma in Russia, from 1250Z and 1254Z on 22 June 2018.
  • In the vicinity of 64.00N, 138.00W, in the Yukon Territory, in lands governed by the Tr’ondëk Hwëch’in, between 0046Z and 0050Z on 23 June 2018.


Predictions are based on a “Best Four” analysis to illustrate the worst case scenario and are provided for situational awareness only.

You may view the full analysis as provided by the GPS Operations Center.

Please report any outages through the NAVCEN Report a GPS Problem page.

This blog is not a replacement or substitute for the formal posting of regulations and updates or existing processes for receiving formal feedback of the same. Links provided on this blog will direct the reader to official source documents, such as the Federal Register, Homeport and the Code of Federal Regulations. These documents remain the official source for regulatory information published by the Coast Guard.

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