Military Exercises To Jam GPS
The Federal Aviation Administration has announced that military exercises through Jan. 24 that will include jamming GPS signals for periods of several hours each day. The exercises will happen about 60 miles off the Florida-Georgia border, and resulting interference will extend 400 nautical miles at high altitudes down to 180 nautical miles at 50 feet above sea level. The Coast Guard has not issued any alerts to the boating public, but that doesn't mean marine GPS won't be affected.

The Aircraft Owners and Pilots Association is complaining that these jamming sessions can pose a threat to airplanes.
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"AOPA is aware of hundreds of reports of interference to aircraft during events around the country for which notices to airmen were issued, and we consider the risks to GA aircraft highly concerning," Dan Namowitz of AOPA wrote. "In one example, an aircraft lost navigation capability and did not regain it until after landing. Other reports have highlighted aircraft veering off course and heading toward active military airspace—and the wide range of reports makes it clear that interference affects aircraft differently. In some cases, recovery from signal interference may not occur until well after the aircraft exits the jammed area."