Chuck -
"When do the military jam the GPS signals?" It's quite frequently NOTAMed in the UK - often with a large radius, e.g.
AC 5555
07 JUL
1100-1400 30000ft (A1063/02pt)
08 JUL
0715-1015 30000ft (A1063/02pt)
GPS Jamming Activity 5555N 00550W rad 320nm
see
http://www.pprune.org/forums/showthr...threadid=58536
"And where do they do this?" Off the top of my head I can remember Scotland, a NATO exercise in the Iceland-Faroes gap and the Bristol channel. As I said, it's quite common.
HTH