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.

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    (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]