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Blog Editor’s Note: This is the most recent warning issued for GPS disruption by the U.S. Maritime Administration (MARAD). For most of the last four or five years MARAD has had a similar warning active and on the books.

The advisory points out that this is a worldwide problem, but is especially a concern in the eastern Mediterranean. We recommend perusing the Coast Guard website where all the reports are listed. Most are in the eastern Med, but we think you will be surprised by the wide and interesting distribution of others.

Note that while this is a warning about GPS disruption, other GNSS are likely impacted also. Most of the world’s jammers don’t discriminate between systems and interfere with most satnavs.


2021-010-Various-GPS Interference


This revised advisory cancels U.S. Maritime Advisory 2021-004

1. Reference: None.

2. Issue: Instances of significant GPS interference have been reported worldwide in the maritime domain. This interference is resulting in lost or inaccurate GPS signals affecting bridge navigation, GPS-based timing, and communications equipment (include satellite communications equipment). Over the last six months, areas from which multiple instances have been reported include the eastern and central Mediterranean Sea and in the vicinity of the Suez Canal. The U.S. Coast Guard Navigation Center (NAVCEN) web page,, contains a chronological list of recently reported GPS problems.

3. Guidance: Exercise caution when underway and prior to getting underway. The NAVCEN and NATO Shipping Center websites contain information regarding effective navigation practices for vessels experiencing GPS disruption. The information reaffirms safe navigation practices when experiencing GPS disruptions, provides useful details on reporting disruptions, and is intended to generate further discussion within the maritime community about other disruption mitigation practices and procedures. This guidance also recommends reporting such incidents in real time; noting critical information such as the location (latitude/longitude), date, time, and duration of the outage/disruption; and providing photographs or screen shots of equipment failures experienced to facilitate analysis. The NAVCEN information is available at:

4. Contact Information: Maritime GPS disruptions or anomalies should be reported immediately to the NAVCEN at or via phone at 703-313-5900, 24-hours a day. NAVCEN will further disseminate reported instances of GPS interference in this region to the NATO Shipping Center.

5. Cancellation: This message will automatically expire on March 14, 2022.

For more information about U.S. Maritime Alerts and Advisories, including subscription details, please visit