{"data":{"id":"us/47-cfr-101.1528","jurisdiction":"us","citation":"47 CFR 101.1528","heading":"Requirements for aeronautical and maritime links to, from, or between endpoints in motion.","body":"(a) Requirements for aeronautical ground stations and endpoints in motion. (1) Air-to-ground transmissions are permitted only in the 71-76 GHz band.\n(2) Ground-to-air transmissions are permitted only in the 81-86 GHz band.\n(3) Air-to-air transmissions are permitted only between aircraft that are separated by a minimum slant path distance of 50 km.\n(4) Transmissions are only permitted to and from aircraft at altitudes between 10,000 ft and 50,000 ft.\n(5) Ground stations must operate with a minimum elevation angle of 5 degrees and a maximum elevation angle of 45 degrees.\n(6) Ground stations must be located at least 10 km from any existing Non-Federal FSS earth station or Federal facility listed in table 4 to paragraph (c)(2) of this section, absent a coordination agreement with the FSS operator.\n(7) Ground stations must be located at least 150 km from the specific Federal facilities and not within the areas listed in table 3 to paragraph (c)(1) of this section, absent a coordination agreement with the Federal operator.\n(8) Ground stations must be located at least 10 km from any existing Federal or non-Federal fixed station receiver, absent a coordination agreement with the fixed station operator.\n(9) Air-to-air transmissions are permitted in 81-86 GHz subject to the following limitations;\n(i) EIRP signal levels radiated along a line between the airborne transmitter and the latitude and longitude of the observatories in table 3 to paragraph (c)(1) of this section, which must be maintained as the airborne transmitter moves, cannot exceed the levels shown in table 1 to this paragraph (a)(9)(i). Within the range of 150 km and 375 km, the maximum allowable EIRP levels for horizontal distances not listed in table below may be approximated by linear interpolation.\nTable 1 to Paragraph (a)(9)(i)—List of Maximum Allowable EIRP levels, in dBW\nFrequency (GHz) Horizontal distance (km)\n150 175 200 225 250 275 300 325 350 375\n81 −11.2 −8.8 −6.5 −4.2 −1.5 1.1 3.9 6.7 10 13.5\n82 −11.5 −9.2 −6.9 −4.6 −2 0.5 3.2 6 9.2 12.6\n83 −11.7 −9.5 −7.3 −5 −2.4 0 2.7 5.4 8.6 11.9\n84 −11.9 −9.7 −7.5 −5.3 −2.8 −0.4 2.3 4.9 8 11.3\n85 −12.1 −9.9 −7.8 −5.5 −3 −0.7 1.9 4.5 7.6 10.8\n86 −12.2 −10 −7.9 −5.7 −3.3 −0.9 1.7 4.2 7.3 10.5\n(ii) A licensee of aeronautical end points in motion must have a capability to target specific areas which can be added to a “block list” as part of a dynamic link management system. If air-to-air transmission within the main beam of the radio astronomy receiver cannot be avoided, air-to-air transmissions within the radio horizon of the radio astronomy site (as specified in table 2 to this paragraph (a)(9)(ii)) should not occur.\nTable 2 to Paragraph (a)(9)(ii)—Approximate Radio Horizon, in Horizontal Distance\n[km]\nAltitude (m) Approximate radio horizon (km) (horizontal distance)\n10,360 375\n8,000 315\n6,000 260\n5,000 220\n4,000 180\n3,000 125\n(iii) The list of radio astronomy sites may be periodically updated by the NTIA and the FCC. This rule may be superseded by a coordination agreement between the licensee and NSF, in which case the coordination agreement will specify the technical restrictions.\n(10) Air-to-air transmissions in the 71-76 GHz band are subject to the following restrictions:\n(i) EIRP signal levels shall be limited to 20 dBW/1000 MHz towards each military installation listed in table 4 to paragraph (c)(2) that is within 375 km of the airborne transmitter. This 20 dBW/1000 MHz EIRP applies to the power radiated along a line between the airborne transmitter and the latitude and longitude of the military installations in table 4 to paragraph (c)(2) of this section and must be maintained as the airborne transmitter moves. An EIRP of 57 dBW/1000 MHz is allowed in other directions. The list of military installations in table 4 to paragraph (c)(2)of this section may be periodically updated by the NTIA and the FCC. This rule may be superseded by a coordination agreement between the licensee and the Department of Defense (DoD), in which case the coordination agreement will specify the technical restrictions and allow the licensee and DoD to update the list of protected installations in the agreement. The locations of all aeronautical end-point-in-motion ground stations will be provided to NTIA and DoD as part of the coordination process.\n(ii) A licensee of aeronautical end points in motion must have a capability to target specific areas which can be added to a “block list” as part of a dynamic link management system. If air-to-air transmission within the main beam of the radio astronomy receivers associated with the observatories in table 3 to paragraph (c)(1) of this section cannot be avoided, air-to-air transmissions within the radio horizon of the radio astronomy site (as specified in table 2 to paragraph (a)(9)(ii) of this section) should not occur.\n(iii) The list of radio astronomy sites may be periodically updated by the NTIA and the FCC. This rule may be superseded by a coordination agreement between the licensee and NSF, in which case the coordination agreement will specify the technical restrictions.\n(b) Requirements for maritime shore stations, aerostats, and endpoints in motion. (1) Ship-to-shore transmissions are only permitted in the 81-86 GHz band.\n(2) Shore-to-ship transmissions are only permitted in the 71-76 GHz band.\n(3) Shore-to-aerostat transmissions are only permitted in the 71-76 GHz band.\n(4) Aerostat-to-ship transmissions are only permitted in the 71-76GHz band.\n(5) Aerostat-to-shore transmissions are only permitted in the 81-86GHz band.\n(6) Aerostat must not operate above an altitude limit of 1000 ft.\n(7) Ship-to-ship communications are limited to ships located more than 30 km offshore, or closer only where the main beam of the transmit antenna is oriented at least 15 degrees away from any point on the shore.\n(8) Ship stations and aerostat stations must only operate when there is a minimum separation of 150 km to the specific Federal facilities and not within the areas listed in table 3 to paragraph (c)(1) of this section, absent a coordination agreement with the Federal operator.\n(9) Shore-to-ship and ship-to-shore transmission must only occur between stations that are located at least 10 km from the Federal military installations listed in table 4 to paragraph (c)(2) of this section, absent a coordination agreement with the Federal operator.\n(c) Protected Federal sites. (1) RAS and VLBA sites:\nTable 3 to Paragraph (c)(1)\nRAS station name North latitude West longitude\nArizona Radio Observatory (ARO) 12-meter 31°57′11.9″ 111°36′53.6″\nGreen Bank Observatory 38°25′59″ 79°50′23″\nVery Large Array (VLA), Socorro, NM 34°04′44″ 107°37′06″\nOwens Valley Radio Observatory (OVRO), Big Pine, CA 37°14′02″ 118°16′55″\nHaystack Observatory, Westford, MA 42°37′24″ 071°29′18″\nNational Radio Astronomy Observatory, Very Long Baseline Array Stations:\nBrewster, WA 48°07′52″ 119°41′00″\nFort Davis, TX 30°38′06″ 103°56′41″\nHancock, NH 42°56′01″ 71°59′12″\nKitt Peak, AZ 31°57′23″ 111°36′45″\nLos Alamos, NM 35°46′30″ 106°14′44″\nMauna Kea, HI 19°48′05″ 155°27′20″\nNorth Liberty, IA 41°46′17″ 91°34′27″\nOwens Valley, CA 37°13′54″ 118°16′37″\nPie Town, NM 34°18′04″ 108°07′09″\nSaint Croix, VI 17°45′24″ 64°35′01″\nNational Radio Quiet Zone Rectangular area between latitudes 37°30′ N and 39°15′ N, and longitudes 78°30′ W and 80°30′ W.\nNext-generation Very Large Array (ngVLA) Rectangular area between latitudes 31°22′1.9″ N and 34°23′10″ N, and longitudes 109°1′53.4″ W and 103°4′39″ W.\n(2) Military installations:\nTable 4 to Paragraph (c)(2)\nMilitary installation Latitude Longitude\nRedstone Arsenal, AL 34°41′42″ N 086°39′04″ W\nFort Huachuca, AZ 31°33′18″ N 110°20′59″ W\nYuma Proving Ground, AZ 33°01′02″ N 114°15′05″ W\nBeale AFB, CA 39°06′41″ N 121°21′36″ W\nCamp Parks Reserve Forces Training Area, CA 34°43′00″ N 121°54′08″ W\nChina Lake Naval Air Weapons Station, CA 35°41′05″ N 117°41′19″ W\nEdwards AFB, CA 34°54′58″ N 117°56′07″ W\nFort Irwin, CA 35°16′22″ N 116°41′05″ W\nMarine Corps Air Ground Combat Center, CA 34°13′54″ N 116°03′42″ W\nBuckley AFB, CO 39°42′36″ N 104°45′29″ W\nSchriever AFB, CO 38°48′12″ N 104°31′32″ W\nFort Gordon, GA 33°25′14″ N 082°09′09″ W\nNaval Satellite Operations Center, GU 13°34′55″ N 144°50′50″ E\nNaval Computer and Telecomm Area Master Station, Pacific, HI 21°31′16″ N 157°59′57″ W\nFort Detrick, MD 39°26′08″ N 077°25′38″ W\nNellis AFB, NV 36°14′29″ N 115°03′03″ W\nNevada Test Site, NV 38°33′41″ N 116°42′30″ W\nTonapah Test Range Airfield, NV 37°47′56″ N 116°46′51″ W\nCannon AFB, NM 34°23′23″ N 103°19′06″ W\nWhite Sands Missile Range, NM 32°56′38″ N 106°25′11” W\nDyess AFB, TX 31°10′10″ N 099°41′01″ W\nFort Bliss, TX 31°48′45″ N 106°25′17″ W\nFort Sam Houston, TX 29°26′34″ N 098°26′33″ W\nGoodfellow AFB, TX 31°26′05″ N 100°24′11″ W\nKelly AFB, TX 29°22′51″ N 098°34′40″ W\nUtah Test and Training Range, UT 40°12′00″ N 112°54′00″ W\nFort Belvoir, VA 38°43′08″ N 077°09′15″ W\nNaval Satellite Operations Center, VA 36°34′00″ N 076°14′00″ W","path":["Title 47—Telecommunication","CHAPTER I—FEDERAL COMMUNICATIONS COMMISSION","SUBCHAPTER D—SAFETY AND SPECIAL RADIO SERVICES","PART 101—FIXED MICROWAVE SERVICES","Subpart Q—Service and Technical Rules for the 70/80/90 GHz Bands"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-47.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:28Z","sha256":"ac81ddd221272d32f3334d4188f985c71edb26f7e98e8b726fb2732bfb174154","source_id":"us-cfr","stale":true,"prev":"us/47-cfr-101.1527","next":"us/47-cfr-201.0"},"notice":"GroundRules: Original legal text. Not legal advice."}