Military Secretive About GPS Blackout Over California: 'Testing Something That Disrupts GPS Over a Huge Area'
(https://www.davidicke.com/wp-content/uploads/2016/06/Screen-shot-2016-06-08-at-3.57.05-PM-768x538.png)
'The U.S. military is planning a series of tests near the West Coast that will result in GPS outages all across the area.
The FAA put out a notice warning about disruptions that may affect aircraft in general, and particularly those reliant upon GPS that testing based at the Navy's China Lake Naval Weapons Center, some 150 miles north of Los Angeles during June 9, 21,23, 28 and 30.'
Read more: Military Secretive About GPS Blackout Over California: 'Testing Something That Disrupts GPS Over a Huge Area'
https://www.davidicke.com/article/374627/military-secretive-gps-blackout-california-testing-something-disrupts-gps-huge-area
If I'm not mistaken, the same thing happened last year on the East Coast, so it looks like something they do with some regularity.
Edited to add that last year it wasn't the GPS system that was affected, it was a different flight system, as seen here (http://www.thelivingmoon.com/forum/index.php?topic=8174.msg118343#msg118343).