This is a recording of NASA 897 (F-15) with an emergency during flight ops north of Los Angeles today. He declared an emergency (due to loss of pressurization) and requested immediate descent. According to FlightAware (see link), he was at FL500 and then started a rapid descent about 2:58 p.m. Pacific time. http://flightaware.com/live/flight/NASA897/history/20130412/1800Z/KEDW/KEDW
Attached communications are with LA Center on 369.9 (Ultra-High Altitude Frequency). Also on the frequency is Torch 08 (which I've seen referenced as a "B1" call sign out of Edwards). NASA 809(U-2) was also up in the air today doing a regular diagonal pattern across Southern California at FL600. Not sure what they were up to but 369.9 was busy.
I am assuming he landed without incident at Edwards but would appreciate if anyone heard any details.