Sec.  87.345   Scope of service.

   Aeronautical utility mobile stations provide communications for vehicles
   operating on an airport movement area. An airport movement area is defined
   as the runways, taxiways and other areas utilized for taxiing, takeoff and
   landing of aircraft, exclusive of loading ramp and parking areas.

   (a) An aeronautical utility mobile station must monitor its assigned
   frequency during periods of operation.

   (b) At an airport which has a control tower, control tower remote
   communications outlet station (RCO) or FAA flight service station in
   operation, communications by an aeronautical utility mobile station are
   limited to the management of ground vehicular traffic.

   (c) Aeronautical utility mobile stations which operate on the airport's
   unicom frequency or the frequency 122.900 MHz are authorized only to
   transmit information relating to safety, such as runway conditions and
   hazards on the airport. These stations are authorized primarily for
   monitoring communications from and to aircraft approaching or departing the
   airport.

   (d) Transmissions by an aeronautical utility mobile station are subject to
   the control of the control tower, the FAA flight service station or the
   unicom, as appropriate. When requested by the control tower, the flight
   service station or the unicom, an aeronautical utility station must
   discontinue transmitting immediately.

   (e) Communications between aeronautical utility mobile stations are not
   authorized.

   [ 53 FR 28940 , Aug. 1, 1988, as amended at  55 FR 7333 , Mar. 1, 1990;  55 FR 30464 , July 26, 1990]