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FAA warns that GPS on the West Coast may be unreliable due to secret tests this month

GPS over Earth
If you’re flying a plane in the Southwest U.S. on certain days this month, you might want to reconsider those plans. The FAA warns that on June 7, 9, 21, 23, 28, and 30 between 9:30 a.m. and 3:30 p.m. local time the GPS network might be unavailable. The reason? We don’t know, as the tests are pretty much a secret.

What it looks to be, based on an FAA advisory, is some type of test of a jamming device. Those of us on the ground shouldn’t notice any change, but pilots will likely lose the capability to connect to GPS satellites in the area during the interference testing periods.

The tests originate from China Lake, California, the location of the Navy’s Naval Air Weapons Center. While the jamming will only affect GPS units at 50 feet above ground level close to the source of the jamming, GPS units up to 40,000 feet up would be affected as far away as southern Oregon and Idaho to the north, western Colorado and New Mexico to the east, and much of northwestern Mexico and Baja California to the south.

Attempts to get clarification from the Navy have not resulted in any further information. While the Navy is aware of the FAA advisory, it wouldn’t provide further details on the tests themselves. It’s a potentially problematic issue for some pilots, especially those piloting Embraer Phenom 300 business jets.

Those planes are being asked to avoid the testing area completely during these times, as their flight stability controls rely heavily on GPS systems. Given these are fairly popular areas among the jet-setting West Coasters, we’re sure this will inconvenience more than a few celebrities and tech execs this month.

Expected flight levels where the jamming will reach during the tests.
Expected flight levels where the jamming will reach during the tests. FAA

At the same time, GPS jamming has become so easy and cheap to do that it’s not unexpected that the U.S. military may want to take a closer look at the potential effects it might have on military aircraft. While conspiracy theorists might want to suggest that the military is doing this to jam out GPS if it needs to, they might also want to consider that it could have defensive purposes as well.

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