The U.S. military have begun a mysterious set of drills on the West coast of America that they say will jam GPS signals for six hours a day. The FAA issued an advisory warning pilots that the global positioning systems (GPS) could be unresponsive this month, but have refused to say why. Gizmodo.com reports: On June 7, 9, 21, 23, 28, and 30th the GPS interference testing will be taking place between 9:30am and 3:30pm Pacific time. But if you're on the ground, you probably won't notice interference. The testing will be centered on China Lake, California—home to the Navy's 1.1 million acre Naval Air Weapons Center in the Mojave Desert. The potentially lost signals will stretch hundreds of miles in each direction and will affect various types of GPS, reaching the furthest at higher altitudes. But the jamming will only affect aircraft above 50 feet. I gave the Naval Air Warfare Center Weapons Division a call yesterday, but they couldn't tell me much. "We're aware of the flight advisory,"