The following NOTAM has been circulated by the FAA:

!FDC 1/4311 ZLA FI/T … SPECIAL NOTICE … SOUTHERN CALIFORNIA COASTLINE. EFFECTIVE 1111141730-1111180130 UTC. AIRCRAFT OPERATORS ARE ADVISED THAT THE DEPARTMENT OF DEFENSE WILL BE CONDUCTING TESTING IN THE WARNING AREAS ADJACENT TO THE SOUTHERN CALIFORNIA COASTLINE. AFTER A REVIEW OF THE IMPACTED AREAS AND THE DOD OPERATIONS BEING CONDUCTED, ANALYSIS INDICATES A LOW LIKELIHOOD OF IMPACT TO AVIATION. HOWEVER, IN THE INTEREST OF FLIGHT SAFETY, PILOTS/FLIGHT CREW MEMBERS EXPERIENCING ANOMALIES TO ANY FLIGHT DECK SYSTEM, IN PARTICULAR TCAS, SHOULD REPORT THEM IMMEDIATELY TO ATC. FAA HEADQUARTERS, AIR TRAFFIC SYSTEMS OPERATIONS SECURITY, 202-493-5107, IS THE FAA COORDINATION FACILITY.

What does it mean? Sounds like some sort of electronic devices are going to be tested and there may be intereference with cockpit systems. The reference to TCAS suggests that they will be using something to do with radar.

Be careful up there!