The navy has described the tests as “GPS Interference Testing”.

The FAA has warned pilots that this month the U.S. military will be conducting experiments at the Naval Air Weapons Center in the Mojave Desert which are likely to affect the GPS instruments in planes.

These are classified tests, so obviously the military wont be very forthcoming with the details. Clues can however be got from the Notice to Airmen (NOTAM) by the FAA, which describes the tests as “GPS Interference Testing”.

The Weapons Center has told Gizmodo that these GPS tests relates to “general testing for [their] ranges.”

Although it could be something more secretive and mysterious, it could also be defensive tests against enemy drones and aircrafts. With very few available details, all you need to know that is that the military has already begun the tests, they are centered around the Navy’s 1.1 million acre installation in China Lake. The jammers being tested will affect GPS signals located above 50ft, so you will hardly feel their effect on the ground.

The area being covered by the jammers is like an ice cream cone, i.e. the higher you go, the wider is the area being covered (jammed). So at 40,000ft their jammers can block the signal of GPS instruments from California to Oregon.

Interestingly, although the U.S. Navy has warned all pilots of possible outages, it has specifically requested Embraer Phenom 300 business jets to avoid the affected locations this month.

Test days are, June 7, June 9, June 21, June 23, June 28 and 30^th from 9:30AM to 3:30PM Pacific time.