GPS jamming
 

It does happen.* Checking on with Albuquerque Center in the vicinity of the White Sands Missile Range the reply was "Expect GPS Jamming for the next 10-15 minutes."* I would imagine it is only a local phenomenon but I don't know.* The airplane didn't seem to notice as we have 5 VOR recievers and 3 Inertial Reference units(and 2 GPSs).

RE: GPS jamming
 

They do that around naval installations and ships sometimes as well. It's pretty easy to do... just broadcast on a certain frequency (I should have it written down somewhere). Doesn't take much power, since the signals are so weak anyway.