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International Air Distress
The aircraft emergency frequency (also known as GUARD) is a frequency used on the aircraft band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air Distress (IAD) or VHF Guard, and 243.0 MHz—the second harmonic of VHF guard—for military use, also known as Military Air Distress (MAD) or UHF Guard. Earlier emergency locator transmitters (ELTs) used the guard frequencies to transmit, but an additional frequency of 406 MHz is used by a more modern emergency locator transmitter. History The choice of 121.5 MHz was made by ICAO in conjunction with ARINC and the ITU. Monitoring In the United States, the emergency frequency is monitored by most air traffic control towers, FSS services, national air traffic control centers, military air defense and other flight and emergency services, as well as by many commercial aircraft. The notice to airmen FDC 4/4386 requires "…all aircr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is equal to one event per second. The period is the interval of time between events, so the period is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times a minute (2 hertz), the period, —the interval at which the beats repeat—is half a second (60 seconds divided by 120 beats). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. Definitions and units For cyclical phenomena such as oscillations, waves, or for examples of simple harmonic motion, the term ''frequency'' is defined as the number of cycles or vibrations per unit of time. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Telecommunications
International is an adjective (also used as a noun) meaning "between nations". International may also refer to: Music Albums * ''International'' (Kevin Michael album), 2011 * ''International'' (New Order album), 2002 * ''International'' (The Three Degrees album), 1975 *''International'', 2018 album by L'Algérino Songs * The Internationale, the left-wing anthem * "International" (Chase & Status song), 2014 * "International", by Adventures in Stereo from ''Monomania'', 2000 * "International", by Brass Construction from ''Renegades'', 1984 * "International", by Thomas Leer from ''The Scale of Ten'', 1985 * "International", by Kevin Michael from ''International'' (Kevin Michael album), 2011 * "International", by McGuinness Flint from ''McGuinness Flint'', 1970 * "International", by Orchestral Manoeuvres in the Dark from '' Dazzle Ships'', 1983 * "International (Serious)", by Estelle from '' All of Me'', 2012 Politics * Political international, any transnational organization of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Communication
An emergency is an urgent, unexpected, and usually dangerous situation that poses an immediate risk to health, life, property, or environment and requires immediate action. Most emergencies require urgent intervention to prevent a worsening of the situation, although in some situations, mitigation may not be possible and agencies may only be able to offer palliative care for the aftermath. While some emergencies are self-evident (such as a natural disaster that threatens many lives), many smaller incidents require that an observer (or affected party) decide whether it qualifies as an emergency. The precise definition of an emergency, the agencies involved and the procedures used, vary by jurisdiction, and this is usually set by the government, whose agencies (emergency services) are responsible for emergency planning and management. Defining an emergency An incident, to be an emergency, conforms to one or more of the following, if it: * Poses an immediate threat to life, hea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Traffic Control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots. Air traffic controllers monitor the location of aircraft in their assigned airspace by radar and communicate with the pilots by radio. To prevent collisions, ATC enforces traffic separation rules, which ensure each aircraft maintains a minimum amount of empty space around it at all times. In many countries, ATC provides services to all private, military, and commercial aircraft operating within its airspace. Depending on the type of flight and the class of airspace, ATC may issue ''instructions'' that pilots are required to obey, or ''advisories'' (known as ''flight infor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transponder (aeronautics)
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 in identifying them on air traffic control radar. Airborne Collision Avoidance System, Collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other. Air traffic control units use the term "squawk" when they are assigning an aircraft a transponder code, ''e.g.'', "Squawk 7421". Squawk thus can be said to mean "select transponder code" or "squawking ''xxxx''" to mean "I have selected transponder code ''xxxx''". The transponder receives interrogation from the Secondary Surveillance Radar on 1030 MHz and replies on 1090 MHz. Secondary surveillance radar Secondary surveillance radar (SSR) is referred to as "secondary", to distinguish it fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mayday
Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications. It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organizations such as firefighters, police forces, and transportation organizations also use the term. Convention requires the word be repeated three times in a row during the initial emergency declaration ("Mayday mayday mayday") to prevent it being mistaken for some similar-sounding phrase under noisy conditions, and to distinguish an ''actual'' mayday call from a message ''about'' a mayday call. History The "mayday" procedure word was conceived as a distress call in the early 1920s by Frederick Stanley Mockford, officer-in-charge of radio at Croydon Airport, England. He had been asked to think of a word that would indicate distress and would easily be understood by all pilots and ground staff in an emergency. Since much of the air traffic at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distress Signal
A distress signal, also known as a distress call, is an internationally recognized means for obtaining help. Distress signals are communicated by transmitting radio signals, displaying a visually observable item or illumination, or making a sound audible from a distance. A distress signal indicates that a person or group of people, ship, aircraft, or other vehicle is threatened by a serious or imminent danger and requires immediate assistance.Aeronautical Information Manual U.S. Federal Aviation Administration, 2016 Use of distress signals in other circumstances may be against local or . An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airband
Airband or aircraft band is the name for a group of frequencies in the VHF radio spectrum allocated to radio communication in civil aviation, sometimes also referred to as ''VHF'', or phonetically as ''"Victor"''. Different sections of the band are used for radionavigational aids and air traffic control. In most countries a license to operate airband equipment is required and the operator is tested on competency in procedures, language and the use of the phonetic alphabet. Spectrum usage The VHF airband uses the frequencies between 108 and 137 MHz. The lowest 10 MHz of the band, from 108 to 117.95 MHz, is split into 200 narrow-band channels of 50 kHz. These are reserved for navigational aids such as VOR beacons, and precision approach systems such as ILS localizers. , most countries divide the upper 19 MHz into 760 channels for amplitude modulation voice transmissions, on frequencies from 118 to 136.975 MHz, in steps of 25 kHz. In Europ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air-ground Radiotelephone Service
Air-ground radiotelephone service is a system which allows voice calls and other communication services to be made from an aircraft to either a satellite or land based network. The service operates via a transceiver mounted in the aircraft on frequency assignment authority, designated frequency, frequencies. In the US these frequencies have been allocated by the Federal Communications Commission. The system is used in both commercial and general aviation services. Licensees may offer a wide range of telecommunications services to passengers and others on aircraft. Design A U.S. air-ground radiotelephone transmits a radio signal in the 849 to 851 Hertz, megahertz range; this signal is sent to either a receiving ground station or a communications satellite depending on the design of the particular system. ''"Commercial aviation air-ground radiotelephone service licensees operate in the 800 MHz band and can provide communication services to all aviation markets, including commercial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NOAA
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditions, charts the seas, conducts deep sea exploration, and manages fishing and protection of marine mammals and endangered species in the U.S. exclusive economic zone. Purpose and function NOAA's specific roles include: * ''Supplying Environmental Information Products''. NOAA supplies to its customers and partners information pertaining to the state of the oceans and the atmosphere, such as weather warnings and forecasts via the National Weather Service. NOAA's information services extend as well to climate, ecosystems, and commerce. * ''Providing Environmental Stewardship Services''. NOAA is a steward of U.S. coastal and marine environments. In coordination with federal, state, local, tribal and international authorities, NOAA manages the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
