Editing Airborne radio relay

'''Airborne radio relay''' is a technique employing aircraft fitted with [[radio relay]] stations for the purpose of increasing the range, flexibility, or physical [[security]] of [[Telecommunications|communications]] systems.<ref>[http://www.its.bldrdoc.gov/fs-1037/dir-002/_0220.htm Definition: airborne radio relay], ''[[Federal Standard 1037C]]'', [[General Services Administration]], August 23, 1996.</ref> The aircraft may be manned or [[unmanned aerial vehicle]]s.<ref>{{Cite news|url=http://cimsec.org/communication-relay-drones/4134|title=A Relay Race: Communication Relay Drones|date=2013-02-12|work=Center for International Maritime Security|access-date=2018-11-01|language=en-US}}</ref>

==Use in Vietnam==
[[Image:C-7 Caribou.jpg|thumb|250px|A C-7 Caribou aircraft as used by the 1st Cavalry Division for airborne radio relay.]]
One of the first uses of airborne radio relay was by the [[United States Army]]'s [[1st Cavalry Division (United States)|1st Cavalry Division]] in the [[Battle of Ia Drang]] during the [[Vietnam War]], which employed the technique to improve communications with commanders at headquarters. The action of war had shifted to the borders of [[Laos]] and [[Cambodia]], where the hilly terrain made the monetary and human cost of seizing and holding high ground, and airlifting and installing radio relay equipment prohibitive. In 1968, the [[United States Department of the Army|Department of the Army]] provided four specially-equipped relay aircraft to the Division, which proved invaluable throughout the country, in particular, during the 1st Cavalry Division's relief of [[Khe Sanh]] in 1968.<ref name="rienzi">{{cite book |last=Rienzi |first=Thomas Matthew |title=Vietnam Studies: Communications-Electronics 1962-1970 |url=http://www.history.army.mil/books/Vietnam/Comm-El/index.htm |archive-url=https://web.archive.org/web/20071213204023/http://www.history.army.mil/books/Vietnam/Comm-El/index.htm |url-status=dead |archive-date=December 13, 2007 |year=1972 |publisher=[[United States Department of the Army]] |location=[[Washington, D.C.]] |chapter=Chapter X: Special Communications Operations and Innovations |chapter-url=http://www.history.army.mil/books/Vietnam/Comm-El/ch10.htm }}</ref>

The use of airborne radio relay was a great success, although two problems arose during the Vietnam War. The first was the limitations of the aircraft used as relays. The 1st Cavalry Division had originally used [[de Havilland Canada DHC-4 Caribou|C-7 Caribou]]s as the relay aircraft, but when these planes were turned over to the [[United States Air Force|Air Force]], the equipment was installed in single-engine [[de Havilland Canada DHC-3 Otter|Otter]] aircraft, which were too underpowered to carry the heavy equipment required for relay. Eventually, the [[1st Signal Brigade (United States)|1st Signal Brigade]] was provided with six specially-equipped [[Beechcraft King Air|U-21]] aircraft for use in relay operations. The second problem was that of [[Electromagnetic interference|radio frequency interference]]: the limited frequency spectrum in use for combat radios meant that relay aircraft often interfered with the communication of ground units when their frequencies were overridden by the airborne units. The Army eventually assigned certain frequencies for airborne relay only, although this further limited the frequencies available to ground units.<ref name="rienzi" />

==See also==
*[[Battlefield Airborne Communications Node]]

==References==

{{Reflist}}

{{Telecommunications}}

{{DEFAULTSORT:Airborne Radio Relay}}
[[Category:Telecommunications techniques]]
[[Category:Aviation communications]]