Eric C. Weaver wrote:

Stubby wrote:

The funny thing about using AM stations is the US Government fielded
the old CONELRAD system to prevent the "enemy" from doing this during
an attack. That threat is minimal these days, NDBs are going away,
but the CONELRAD system keeps being revised. I hear several tests
every week.


The old CONELRAD (CONtrol of ELectromagnetic RADiation) system involved
all AM stations retuning to either 640 or 12-something and switching on
and off. It became obsolete when other missile-lobbing nations
developed inertial navigation, in the '60s or so.

The modern EAS has about as much to do with the old CONELRAD program as
GPSes do with NDBs.


GPS's have a lot to do with NDBs. An approach-certified GPS is a legal
substitute for an ADF. and it's a heck of a lot easier to fly NDB
radials using GPS than ADF -- no math or card twisting required, just
get the bearing number right and then make the track number match it.