Sec. 87.5  Definitions.

    Aeronautical advisory station (unicom). An aeronautical station used 
for advisory and civil defense communications primarily with private 
aircraft stations.
    Aeronautical enroute station. An aeronautical station which 
communicates with aircraft stations in flight status or with other 
aeronautical enroute stations.
    Aeronautical fixed service. A radiocommunication service between

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specified fixed points provided primarily for the safety of air 
navigation and for the regular, efficient and economical operation of 
air transport. A station in this service is an aeronautical fixed 
station.
    Aeronautical Mobile Off-Route (OR) Service. An aeronautical mobile 
service intended for communications, including those relating to flight 
coordination, primarily outside national or international civil air 
routes.(RR)
    Aeronautical Mobile Route (R) Service. An aeronautical mobile 
service reserved for communications relating to safety and regularity of 
flight, primarily along national or international civil air routes.(RR)
    Aeronautical Mobile-Satellite Off-Route (OR) Service. An 
aeronautical mobile-satellite service intended for communications, 
including those relating to flight coordination, primarily outside 
national and international civil air routes.(RR)
    Aeronautical Mobile-Satellite Route (R) Service. An aeronautical 
mobile-satellite service reserved for communications relating to safety 
and regularity of flights, primarily along national or international 
civil air routes.(RR)
    Aeronautical Mobile-Satellite Service. A mobile-satellite service in 
which mobile earth stations are located on board aircraft.
    Aeronautical mobile service. A mobile service between aeronautical 
stations and aircraft stations, or between aircraft stations, in which 
survival craft stations may also participate; emergency position-
indicating radiobeacon stations may also participate in this service on 
designated distress and emergency frequencies.
    Aeronautical multicom station. An aeronautical station used to 
provide communications to conduct the activities being performed by, or 
directed from, private aircraft.
    Aeronautical radionavigation service. A radionavigation service 
intended for the benefit and for the safe operation of aircraft.
    Aeronautical search and rescue station. An aeronautical station for 
communication with aircraft and other aeronautical search and rescue 
stations pertaining to search and rescue activities with aircraft.
    Aeronautical station. A land station in the aeronautical mobile 
service. In certain instances an aeronautical station may be located, 
for example, on board ship or on a platform at sea.
    Aeronautical utility mobile station. A mobile station used on 
airports for communications relating to vehicular ground traffic.
    Air carrier aircraft station. A mobile station on board an aircraft 
which is engaged in, or essential to, the transportation of passengers 
or cargo for hire.
    Aircraft earth station (AES). A mobile earth station in the 
aeronautical mobile-satellite service located on board an aircraft.
    Aircraft station. A mobile station in the aeronautical mobile 
service other than a survival craft station, located on board an 
aircraft.
    Airport. An area of land or water that is used or intended to be 
used for the landing and takeoff of aircraft, and includes its buildings 
and facilities, if any.
    Airport control tower (control tower) station. An aeronautical 
station providing communication between a control tower and aircraft.
    Automatic weather observation station. A land station located at an 
airport and used to automatically transmit weather information to 
aircraft.
    Aviation service organization. Any business firm which maintains 
facilities at an airport for the purposes of one or more of the 
following general aviation activities: (a) Aircraft fueling; (b) 
aircraft services (e.g. parking, storage, tie-downs); (c) aircraft 
maintenance or sales; (d) electronics equipment maintenance or sales; 
(e) aircraft rental, air taxi service or flight instructions; and (f) 
baggage and cargo handling, and other passenger or freight services.
    Aviation services. Radio-communication services for the operation of 
aircraft. These services include aeronautical fixed service, 
aeronautical mobile service, aeronautical radiodetermination service, 
and secondarily, the handling of public correspondence on frequencies in 
the maritime mobile and maritime mobile satellite services to and from 
aircraft.

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    Aviation support station. An aeronautical station used to coordinate 
aviation services with aircraft and to communicate with aircraft engaged 
in unique or specialized activities. (See subpart K)
    Civil Air Patrol station. A station used exclusively for 
communications of the Civil Air Patrol.
    Emergency locator transmitter (ELT). A transmitter of an aircraft or 
a survival craft actuated manually or automatically that is used as an 
alerting and locating aid for survival purposes.
    Emergency locator transmitter (ELT) test station. A land station 
used for testing ELTs or for training in the use of ELTs.
    Expendable Launch Vehicle (ELV). A booster rocket that can be used 
only once to launch a payload, such as a missile or space vehicle.
    Flight test aircraft station. An aircraft station used in the 
testing of aircraft or their major components.
    Flight test land station. An aeronautical station used in the 
testing of aircraft or their major components.
    Glide path station. A radionavigation land station which provides 
vertical guidance to aircraft during approach to landing.
    Instrument landing system (ILS). A radionavigation system which 
provides aircraft with horizontal and vertical guidance just before and 
during landing and, at certain fixed points, indicates the distance to 
the reference point of landing.
    Instrument landing system glide path. A system of vertical guidance 
embodied in the instrument landing system which indicates the vertical 
deviation of the aircraft from its optimum path of descent.
    Instrument landing system localizer. A system of horizontal guidance 
embodied in the instrument landing system which indicates the horizontal 
deviation of the aircraft from its optimum path of descent along the 
axis of the runway or along some other path when used as an offset.
    Land station. A station in the mobile service not intended to be 
used while in motion.
    Localizer station. A radionavigation land station which provides 
horizontal guidance to aircraft with respect to a runway center line.
    Marker beacon station. A radionavigation land station in the 
aeronautical radionavigation service which employs a marker beacon. A 
marker beacon is a transmitter which radiates vertically a distinctive 
pattern for providing position information to aircraft.
    Mean power (of a radio transmitter). The average power supplied to 
the antenna transmission line by a transmitter during an interval of 
time sufficiently long compared with the lowest frequency encountered in 
the modulation taken under normal operating conditions.
    Microwave landing system. An instrument landing system operating in 
the microwave spectrum that provides lateral and vertical guidance to 
aircraft having compatible avionics equipment.
    Mobile service. A radiocommunication service between mobile and land 
stations, or between mobile stations. A mobile station is intended to be 
used while in motion or during halts at unspecified points.
    Operational fixed station. A fixed station, not open to public 
correspondence, operated by and for the sole use of persons operating 
their own radiocommunication facilities in the public safety, 
industrial, land transportation, marine, or aviation services.
    Peak envelope power (of a radio transmitter). The average power 
supplied to the antenna transmission line by a transmitter during one 
radio frequency cycle at the crest of the modulation envelope taken 
under normal operating conditions.
    Private aircraft station. A mobile station on board an aircraft not 
operated as an air carrier. A station on board an air carrier aircraft 
weighing less than 12,500 pounds maximum certified takeoff gross weight 
may be licensed as a private aircraft station.
    Racon station. A radionavigation land station which employs a racon. 
A racon (radar beacon) is a transmitter-receiver associated with a fixed 
navigational mark, which when triggered by a radar, automatically 
returns a distinctive signal which can appear on the display of the 
triggering radar, providing range, bearing and identification 
information.

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    Radar. A radiodetermination system based upon the comparison of 
reference signals with radio signals reflected, or re-transmitted, from 
the position to be determined.
    Radio altimeter. Radionavigation equipment, on board an aircraft or 
spacecraft, used to determine the height of the aircraft or spacecraft 
above the Earth's surface or another surface.
    Radiobeacon station. A station in the radionavigation service the 
emissions of which are intended to enable a mobile station to determine 
its bearing or direction in relation to the radiobeacon station.
    Radiodetermination service. A radiocommuncation service which uses 
radiodetermination. Radiodetermination is the determination of the 
position, velocity and/or other characteristics of an object, or the 
obtaining of information relating to these parameters, by means of the 
propagation of radio waves. A station in this service is called a 
radiodetermination station.
    Radiolocation service. A radiodetermination service for the purpose 
of radiolocation. Radiolocation is the use of radiodetermination for 
purposes other than those of radionavigation.
    Radionavigation land test stations. A radionavigation land station 
which is used to transmit information essential to the testing and 
calibration of aircraft navigational aids, receiving equipment, and 
interrogators at predetermined surface locations. The Maintenance Test 
Facility (MTF) is used primarily to permit maintenance testing by 
aircraft radio service personnel. The Operational Test Facility (OTF) is 
used primarily to permit the pilot to check a radionavigation system 
aboard the aircraft prior to takeoff.
    Radionavigation service. A radiodetermination service for the 
purpose of radionavigation. Radionavigation is the use of 
radiodetermination for the purpose of navigation, including obstruction 
warning.
    Re-usable launch vehicle (RLV). A booster rocket that can be 
recovered after launch, refurbished and re-launched.
    Surveillance radar station. A radionavigation land station in the 
aeronautical radionavigation service employing radar to display the 
presence of aircraft within its range.
    Survival craft station. A mobile station in the maritime or 
aeronautical mobile service intended solely for survival purposes and 
located on any lifeboat, life raft or other survival equipment.
    VHF Omni directional range station (VOR). A radionavigation land 
station in the aeronautical radionavigation service providing direct 
indication of the bearing (omni-bearing) of that station from an 
aircraft.
[ 53 FR 28940 , Aug. 1, 1988, as amended at  54 FR 11719 , Mar. 22, 1989;  54 FR 49995 , Dec. 4, 1989;  55 FR 4175 , Feb. 7, 1990;  57 FR 45749 , Oct. 5, 
1992]

                  Subpart B--Applications and Licenses