ZNF insider “Methodic Jon” caught Engadget’s coverage of potential GPS interruption and suggested we run a public service announcement. And so we are. From the FAA advisory to pilots:

The Department of Defense will conduct GPS tests on January 20th through February22nd, 2011. During testing, the GPS signal may be unreliable or unavailable.

As you can see from the image above, the potential footprint of GPS service disruption looks quite large. So I rang up the US Coast Guard Navigation Center to better understand how this testing might impact us here on the ground. If I understand correctly, which is not a given, testing could very well effect our GPS equipment. However, at altitudes in this region, the radius of impact is a much more modest 150 miles.

Testing during the month will not be continual or concurrent, but folks in Florida, Georgia, and South Carolina may want to take their GPS guidance with a grain of salt… and possibly resort to some old school MapQuest printouts when visiting unfamiliar locales.