North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...

, a NORDO () aircraft is an aircraft flying without a

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...

. While sometimes used to denote small

general aviation General aviation (GA) is defined by the International Civil Aviation Organization (ICAO) as all civil aviation aircraft operations with the exception of commercial air transport or aerial work, which is defined as specialized aviation services ...

aircraft that are not equipped with a radio, the term is more commonly applied to aircraft that have experienced a radio failure while flying. The term originates from the 5-character uppercase abbreviated notation "''NORDO''" displayed on controllers' radar scopes when an aircraft transmits the "radio failure" code on its

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend word, blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a T ...

. An alternate explanation is that "NO RDO" was the standard note made on maintenance and equipment sheets used in military aviation, starting in the 1930s, as a code to identify planes which needed radio repairs or were not equipped with radios. The term has made its way into standard aviation jargon, used as an adjective or a noun to describe an aircraft without a radio, even among pilots and others who are not air traffic controllers. In-flight radio failure may constitute an emergency, as determined by the pilot. Aircraft equipped with a transponder should indicate a NORDO situation by setting the appropriate

transponder code A transponder (short for ''trans''mitter-res''ponder'' and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist ...

: 7600 ("''seven-six: radio fix''"). NORDO aircraft declaring an emergency are given priority over other aircraft (providing a more serious emergency does not occur on another aircraft). If the radio failure occurs in ''

visual flight rules In aviation, visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better ...

'' (VFR) conditions in an area where radio communication is required, the pilot is expected to continue under VFR and land when feasible. If flying under ''

instrument flight rules In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR). The U.S. Federal Aviation Administration's (FAA) ''Instrument Fly ...

'' (IFR) conditions, and VFR conditions exist or are encountered after the failure, the flight should be continued in VFR conditions and the pilot shall land as soon as practicable. If VFR conditions do not exist, the pilot will then continue the route last assigned by ATC. See FAR 91.185. Air traffic control may re-establish communications with NORDO aircraft by using emergency frequencies, voice features of NAVAIDs, or

aviation light signals In the case of a radio failure or aircraft not equipped with a radio, or in the case of a deaf pilot, air traffic control may use a signal lamp (called a "signal light gun" or "light gun" by the FAA) to direct the aircraft. ICAO The Intern ...

. In the event of one-way communications (i.e. aircraft can receive only), the controller may request the aircraft make identifying turns, flash their navigational lights, transmit codes or IDENT signals on the transponder, rock their wings, etc., to acknowledge clearances or instructions.

References

{{Reflist Air traffic control in the United States Emergency aircraft operations Acronyms