Sorry for the multiple posts. Just found this at;
http://wireless.fcc.gov/services/ind...round_stations.
Note that gliders are specifically mentioned.

"Aviation support stations are airborne and ground stations used for
pilot training, soaring (with gliders), or free ballooning."

Now, what does that mean?

- John

===============

About Ground Stations


The FCC regulates the Aviation Services in cooperation with the
Federal Aviation Administration. Wherever aviation services are
provided in US territory, both FAA and FCC requirements must be met by
anyone who uses aviation radio. The FCC authorizes different types of
aviation ground stations for air-to-ground operations. Flight safety
is the primary purpose of all Aviation Services.

Aeronautical and Fixed ServiceAeronautical advisory stations, also
called Unicom stations, are land stations used for advising pilots of
private aircraft about local airport conditions. They are not used to
control aircraft in flight.

Aeronautical multicom stations provide communications between private
aircraft and a ground facility for temporary, seasonal, or emergency
activities like crop dusting, livestock herding, forest firefighting,
aerial advertising, parachute jumping, etc. In some cases, multicom
stations may be authorized to serve as unicom stations.

Aeronautical enroute stations are used by aircraft owners or operators
for operational control and flight management of their aircraft. They
have access to these stations by cooperative arrangement, but any
pilot with a flight emergency may use these stations without prior
agreement.

Flight test stations are airborne and ground stations used only to
pass information or instructions concerning tests of aircraft or
airborne components.

Aviation support stations are airborne and ground stations used for
pilot training, soaring (with gliders), or free ballooning.

Airport control tower stationsprovide all necessary communications
between an airport control tower and all arriving and departing
aircraft. They are used to maintain an efficient flow of traffic for
aircraft taxiing, landing, and takeoff and for all vehicle movement on
the airfield. For vehicle movement on the airfield, airport control
tower stations communicate with aeronautical utility mobile stations

Automatic weather observation stations provide updated weather
broadcasts for a specific landing area.

Aviation Auxiliary GroupAeronautical search and rescue stations are
used for air-to-ground communications during actual or practice search
and rescue operations, or for search and rescue training.

Aeronautical utility mobile stations are installed in vehicles that
provide maintenance, fire and crash protection, freight handling, or
other group support normally under control tower direction at an
airport. They are used for both operational and emergency
communications.