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Radar and other avionics in the nose of a Cessna Citation I/SP. Cessna501 radar.JPG
Radar and other avionics in the nose of a Cessna Citation I/SP.
F-105 Thunderchief with avionics laid out Republic F-105B with avionics layout 060831-F-1234S-046.jpg
F-105 Thunderchief with avionics laid out

Avionics (a portmanteau of aviation and electronics) are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform.



The term "avionics" was coined in 1949 by Philip J. Klass, senior editor at Aviation Week & Space Technology magazine as a portmanteau of "aviation electronics". [1] [2]

Radio communication was first used in aircraft just prior to World War I. [3] The first airborne radios were in zeppelins, but the military sparked development of light radio sets that could be carried by heavier-than-air craft, so that aerial reconnaissance biplanes could report their observations immediately in case they were shot down. The first experimental radio transmission from an airplane was conducted by the US Navy August 1910. The first aircraft radios transmitted by radiotelegraphy, so they required two-seat aircraft with a second crewman to tap on a telegraph key to spell out messages by Morse code. During World War I, AM voice two way radio sets were made possible in 1917 by the development of the triode vacuum tube, which were simple enough that the pilot in a single seat aircraft could use it while flying.

Radar, the central technology used today in aircraft navigation and air traffic control, was developed by several nations, mainly in secret, as an air defense system in the 1930s during the runup to World War II. Many modern avionics have their origins in World War II wartime developments. For example, autopilot systems that are commonplace today began as specialized systems to help bomber planes fly steadily enough to hit precision targets from high altitudes. [4] Britain's 1940 decision to share its radar technology with its US ally, particularly the magnetron vacuum tube, in the famous Tizard Mission, significantly shortened the war. [5] Modern avionics is a substantial portion of military aircraft spending. Aircraft like the F-15E and the now retired F-14 have roughly 20 percent of their budget spent on avionics. Most modern helicopters now have budget splits of 60/40 in favour of avionics. [6]

The civilian market has also seen a growth in cost of avionics. Flight control systems (fly-by-wire) and new navigation needs brought on by tighter airspaces, have pushed up development costs. The major change has been the recent boom in consumer flying. As more people begin to use planes as their primary method of transportation, more elaborate methods of controlling aircraft safely in these high restrictive airspaces have been invented.[ citation needed ]

Modern avionics

Avionics plays a heavy role in modernization initiatives like the Federal Aviation Administration's (FAA) Next Generation Air Transportation System project in the United States and the Single European Sky ATM Research (SESAR) initiative in Europe. The Joint Planning and Development Office put forth a roadmap for avionics in six areas: [7]


The Aircraft Electronics Association reports $1.73 billion avionics sales for the first three quarters of 2017 in business and general aviation, a 4.1% yearly improvement: 73.5% came from North America, forward-fit represented 42.3% while 57.7% were retrofits as the U.S. deadline of January 1, 2020 for mandatory ADS-B out approach. [8]

Aircraft avionics

The cockpit of an aircraft is a typical location for avionic equipment, including control, monitoring, communication, navigation, weather, and anti-collision systems. The majority of aircraft power their avionics using 14- or 28‑volt DC electrical systems; however, larger, more sophisticated aircraft (such as airliners or military combat aircraft) have AC systems operating at 400 Hz, 115 volts AC. [9] There are several major vendors of flight avionics, including Panasonic Avionics Corporation, Honeywell (which now owns Bendix/King), Universal Avionics Systems Corporation, Rockwell Collins (now Collins Aerospace), Thales Group, GE Aviation Systems, Garmin, Raytheon, Parker Hannifin, UTC Aerospace Systems (now Collins Aerospace), Selex ES (now Leonardo S.p.A.), Shadin Avionics, and Avidyne Corporation.

International standards for avionics equipment are prepared by the Airlines Electronic Engineering Committee (AEEC) and published by ARINC.


Communications connect the flight deck to the ground and the flight deck to the passengers. On‑board communications are provided by public-address systems and aircraft intercoms.

The VHF aviation communication system works on the airband of 118.000 MHz to 136.975 MHz. Each channel is spaced from the adjacent ones by 8.33 kHz in Europe, 25 kHz elsewhere. VHF is also used for line of sight communication such as aircraft-to-aircraft and aircraft-to-ATC. Amplitude modulation (AM) is used, and the conversation is performed in simplex mode. Aircraft communication can also take place using HF (especially for trans-oceanic flights) or satellite communication.

Air navigation is the determination of position and direction on or above the surface of the Earth. Avionics can use satellite navigation systems (such as GPS and WAAS), inertial navigation system (INS), ground-based radio navigation systems (such as VOR or LORAN), or any combination thereof. Some navigation systems such as GPS calculate the position automatically and display it to the flight crew on moving map displays. Older ground-based Navigation systems such as VOR or LORAN requires a pilot or navigator to plot the intersection of signals on a paper map to determine an aircraft's location; modern systems calculate the position automatically and display it to the flight crew on moving map displays.


The Airbus A380 glass cockpit featuring pull-out keyboards and two wide computer screens on the sides for pilots. Airbus A380 cockpit.jpg
The Airbus A380 glass cockpit featuring pull-out keyboards and two wide computer screens on the sides for pilots.

The first hints of glass cockpits emerged in the 1970s when flight-worthy cathode ray tube (CRT) screens began to replace electromechanical displays, gauges and instruments. A "glass" cockpit refers to the use of computer monitors instead of gauges and other analog displays. Aircraft were getting progressively more displays, dials and information dashboards that eventually competed for space and pilot attention. In the 1970s, the average aircraft had more than 100 cockpit instruments and controls. [10] Glass cockpits started to come into being with the Gulfstream G‑IV private jet in 1985. One of the key challenges in glass cockpits is to balance how much control is automated and how much the pilot should do manually. Generally they try to automate flight operations while keeping the pilot constantly informed. [10]

Aircraft flight-control system

Aircraft have means of automatically controlling flight. Autopilot was first invented by Lawrence Sperry during World War I to fly bomber planes steady enough to hit accurate targets from 25,000 feet. When it was first adopted by the U.S. military, a Honeywell engineer sat in the back seat with bolt cutters to disconnect the autopilot in case of emergency. Nowadays most commercial planes are equipped with aircraft flight control systems in order to reduce pilot error and workload at landing or takeoff. [4]

The first simple commercial auto-pilots were used to control heading and altitude and had limited authority on things like thrust and flight control surfaces. In helicopters, auto-stabilization was used in a similar way. The first systems were electromechanical. The advent of fly by wire and electro-actuated flight surfaces (rather than the traditional hydraulic) has increased safety. As with displays and instruments, critical devices that were electro-mechanical had a finite life. With safety critical systems, the software is very strictly tested.

Fuel Systems

Fuel Quantity Indication System (FQIS) monitors the amount of fuel aboard. Using various sensors, such as capacitance tubes, temperature sensors, densitometers & level sensors, the FQIS computer calculates the mass of fuel remaining on board.

Fuel Control and Monitoring System (FCMS) reports fuel remaining on board in a similar manner, but, by controlling pumps & valves, also manages fuel transfers around various tanks.

Collision-avoidance systems

To supplement air traffic control, most large transport aircraft and many smaller ones use a traffic alert and collision avoidance system (TCAS), which can detect the location of nearby aircraft, and provide instructions for avoiding a midair collision. Smaller aircraft may use simpler traffic alerting systems such as TPAS, which are passive (they do not actively interrogate the transponders of other aircraft) and do not provide advisories for conflict resolution.

To help avoid controlled flight into terrain (CFIT), aircraft use systems such as ground-proximity warning systems (GPWS), which use radar altimeters as a key element. One of the major weaknesses of GPWS is the lack of "look-ahead" information, because it only provides altitude above terrain "look-down". In order to overcome this weakness, modern aircraft use a terrain awareness warning system (TAWS).

Flight recorders

Commercial aircraft cockpit data recorders, commonly known as "black boxes", store flight information and audio from the cockpit. They are often recovered from an aircraft after a crash to determine control settings and other parameters during the incident.

Weather systems

Weather systems such as weather radar (typically Arinc 708 on commercial aircraft) and lightning detectors are important for aircraft flying at night or in instrument meteorological conditions, where it is not possible for pilots to see the weather ahead. Heavy precipitation (as sensed by radar) or severe turbulence (as sensed by lightning activity) are both indications of strong convective activity and severe turbulence, and weather systems allow pilots to deviate around these areas.

Lightning detectors like the Stormscope or Strikefinder have become inexpensive enough that they are practical for light aircraft. In addition to radar and lightning detection, observations and extended radar pictures (such as NEXRAD) are now available through satellite data connections, allowing pilots to see weather conditions far beyond the range of their own in-flight systems. Modern displays allow weather information to be integrated with moving maps, terrain, and traffic onto a single screen, greatly simplifying navigation.

Modern weather systems also include wind shear and turbulence detection and terrain and traffic warning systems. [11] In‑plane weather avionics are especially popular in Africa, India, and other countries where air-travel is a growing market, but ground support is not as well developed. [12]

Aircraft management systems

There has been a progression towards centralized control of the multiple complex systems fitted to aircraft, including engine monitoring and management. Health and usage monitoring systems (HUMS) are integrated with aircraft management computers to give maintainers early warnings of parts that will need replacement.

The integrated modular avionics concept proposes an integrated architecture with application software portable across an assembly of common hardware modules. It has been used in fourth generation jet fighters and the latest generation of airliners.

Mission or tactical avionics

Military aircraft have been designed either to deliver a weapon or to be the eyes and ears of other weapon systems. The vast array of sensors available to the military is used for whatever tactical means required. As with aircraft management, the bigger sensor platforms (like the E‑3D, JSTARS, ASTOR, Nimrod MRA4, Merlin HM Mk 1) have mission-management computers.

Police and EMS aircraft also carry sophisticated tactical sensors.

Military communications

While aircraft communications provide the backbone for safe flight, the tactical systems are designed to withstand the rigors of the battle field. UHF, VHF Tactical (30–88 MHz) and SatCom systems combined with ECCM methods, and cryptography secure the communications. Data links such as Link 11, 16, 22 and BOWMAN, JTRS and even TETRA provide the means of transmitting data (such as images, targeting information etc.).


Airborne radar was one of the first tactical sensors. The benefit of altitude providing range has meant a significant focus on airborne radar technologies. Radars include airborne early warning (AEW), anti-submarine warfare (ASW), and even weather radar (Arinc 708) and ground tracking/proximity radar.

The military uses radar in fast jets to help pilots fly at low levels. While the civil market has had weather radar for a while, there are strict rules about using it to navigate the aircraft.[ citation needed ]


Dipping sonar fitted to a range of military helicopters allows the helicopter to protect shipping assets from submarines or surface threats. Maritime support aircraft can drop active and passive sonar devices (sonobuoys) and these are also used to determine the location of enemy submarines.


Electro-optic systems include devices such as the head-up display (HUD), forward looking infrared (FLIR), infrared search and track and other passive infrared devices (Passive infrared sensor). These are all used to provide imagery and information to the flight crew. This imagery is used for everything from search and rescue to navigational aids and target acquisition.


Electronic support measures and defensive aids systems are used extensively to gather information about threats or possible threats. They can be used to launch devices (in some cases automatically) to counter direct threats against the aircraft. They are also used to determine the state of a threat and identify it.

Aircraft networks

The avionics systems in military, commercial and advanced models of civilian aircraft are interconnected using an avionics databus. Common avionics databus protocols, with their primary application, include:

See also


  1. McGough, Michael (August 26, 2005). "In Memoriam: Philip J. Klass: A UFO (Ufologist Friend's Obituary)". Skeptic. Retrieved April 26, 2012.
  2. Dickson, Paul (2009). A Dictionary of the Space Age. JHU Press. p. 32. ISBN   9780801895043.
  3. "Directing Airplanes by Wireless". Telephony. Chicago, IL: Telephony Publishing Corp. 77 (8): 20. August 23, 1919.
  4. 1 2 By Jeffrey L. Rodengen. ISBN   0-945903-25-1. Published by Write Stuff Syndicate, Inc. in 1995. "The Legend of Honeywell."
  5. Reginald Victor Jones (1998). Most Secret War. ISBN   978-1-85326-699-7.
  6. Douglas Nelms (April 1, 2006). "Rotor & Wing: Retro Cockpits".
  7. "NextGen Avionics Roadmap" (PDF). Joint Planning and Development Office. September 30, 2011. Archived from the original (PDF) on April 17, 2012. Retrieved January 25, 2012.
  8. Chad Trautvetter (November 20, 2017). "AEA: Retrofits Lift Avionics Sales through 3Q". AIN.
  9. 400 Hz Electrical Systems
  10. 1 2 Avionics: Development and Implementation by Cary R. Spitzer (Hardcover – December 15, 2006)
  11. Ramsey, James (August 1, 2000). "Broadening Weather Radar's Scope". Aviation Today. Retrieved January 25, 2012.
  12. Fitzsimons, Bernard (November 13, 2011). "Honeywell Looks East While Innovating For Safe Growth". Aviation International News. Retrieved December 27, 2011.

Further reading

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Lockheed S-3 Viking Carrier-based anti-submarine and aerial refueling aircraft

The Lockheed S-3 Viking is a 4-crew, twin-engine turbofan-powered jet aircraft that was used by the U.S. Navy (USN) primarily for anti-submarine warfare. In the late 1990s, the S-3B's mission focus shifted to surface warfare and aerial refueling. The Viking also provided electronic warfare and surface surveillance capabilities to a carrier battle group. A carrier-based, subsonic, all-weather, long-range, multi-mission aircraft, it carried automated weapon systems and was capable of extended missions with in-flight refueling. Because of its characteristic sound, it was nicknamed the "War Hoover" after the vacuum cleaner brand.

Cockpit Area from which a pilot controls an aircraft or vehicle

A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a pilot controls the aircraft.

Head-up display Transparent display presenting data within normal sight lines of the user

A head-up display, also known as a HUD, is any transparent display that presents data without requiring users to look away from their usual viewpoints. The origin of the name stems from a pilot being able to view information with the head positioned "up" and looking forward, instead of angled down looking at lower instruments. A HUD also has the advantage that the pilot's eyes do not need to refocus to view the outside after looking at the optically nearer instruments.

Glass cockpit Aircraft instrumentation system consisting primarily of multi-function electronic displays

A glass cockpit is an aircraft cockpit that features electronic (digital) flight instrument displays, typically large LCD screens, rather than the traditional style of analog dials and gauges. While a traditional cockpit relies on numerous mechanical gauges to display information, a glass cockpit uses several multi-function displays driven by flight management systems, that can be adjusted to display flight information as needed. This simplifies aircraft operation and navigation and allows pilots to focus only on the most pertinent information. They are also popular with airline companies as they usually eliminate the need for a flight engineer, saving costs. In recent years the technology has also become widely available in small aircraft.

Controlled flight into terrain Aviation accident in which a pilot unintentionally flies the aircraft into an obstacle

In aviation, a controlled flight into terrain is an accident in which an airworthy aircraft, under pilot control, is unintentionally flown into the ground, a mountain, a body of water or an obstacle. In a typical CFIT scenario, the crew is unaware of the impending disaster until it is too late. The term was coined by engineers at Boeing in the late 1970s.

Ground proximity warning system Alert system meant to prevent pilots from flying or taxiing into obstacles

A ground proximity warning system (GPWS) is a system designed to alert pilots if their aircraft is in immediate danger of flying into the ground or an obstacle. The United States Federal Aviation Administration (FAA) defines GPWS as a type of terrain awareness warning system (TAWS). More advanced systems, introduced in 1996, are known as enhanced ground proximity warning systems (EGPWS), a modern type of TAWS.

Multi-function display Small screen surrounded by multiple soft keys

A multifunction display (MFD) is a small-screen surrounded by multiple soft keys that can be used to display information to the user in numerous configurable ways. MFDs originated in aviation, first in military aircraft, and later were adopted by commercial aircraft, general aviation, automotive use, and shipboard use.

Aircrew Personnel who operate an aircraft while in flight

Aircrew, also called flight crew, are personnel who operate an aircraft while in flight. The composition of a flight's crew depends on the type of aircraft, plus the flight's duration and purpose.

Aeronautical Radio, Incorporated (ARINC), established in 1929, was a major provider of transport communications and systems engineering solutions for eight industries: aviation, airports, defense, government, healthcare, networks, security, and transportation. ARINC had installed computer data networks in police cars and railroad cars and also maintains the standards for line-replaceable units.

Electronic flight instrument system Display system in an aircrafts cockpit which displays flight information electronically

In aviation, an electronic flight instrument system (EFIS) is a flight instrument display system in an aircraft cockpit that displays flight data electronically rather than electromechanically. An EFIS normally consists of a primary flight display (PFD), multi-function display (MFD), and an engine indicating and crew alerting system (EICAS) display. Early EFIS models used cathode ray tube (CRT) displays, but liquid crystal displays (LCD) are now more common. The complex electromechanical attitude director indicator (ADI) and horizontal situation indicator (HSI) were the first candidates for replacement by EFIS. Now, however, few flight deck instruments cannot be replaced by an electronic display.


In aviation, ACARS is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The protocol was designed by ARINC and deployed in 1978, using the Telex format. More ACARS radio stations were added subsequently by SITA.

Flight management system

A flight management system (FMS) is a fundamental component of a modern airliner's avionics. An FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew to the point that modern civilian aircraft no longer carry flight engineers or navigators. A primary function is in-flight management of the flight plan. Using various sensors to determine the aircraft's position, the FMS can guide the aircraft along the flight plan. From the cockpit, the FMS is normally controlled through a Control Display Unit (CDU) which incorporates a small screen and keyboard or touchscreen. The FMS sends the flight plan for display to the Electronic Flight Instrument System (EFIS), Navigation Display (ND), or Multifunction Display (MFD). The FMS can be summarised as being a dual system consisting of the Flight Management Computer (FMC), CDU and a cross talk bus.

Airborne collision avoidance system

An airborne collision avoidance system operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision. If the risk of collision is imminent, the system initiates a maneuver that will reduce the risk of collision. ACAS standards and recommended practices are mainly defined in annex 10, volume IV, of the Convention on International Civil Aviation. Much of the technology being applied to both military and general aviation today has been undergoing development by NASA and other partners since the 1980s.

Synthetic vision system

A synthetic vision system (SVS) is a computer-mediated reality system for aerial vehicles, that uses 3D to provide pilots with clear and intuitive means of understanding their flying environment.

The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting. In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.

The Capstone Program was a United States government-funded aviation safety program for the state of Alaska, primarily focusing on rural areas of the state. This joint effort – between the Federal Aviation Administration (FAA), the Alaska Pilot's Association, commercial operators, the University of Alaska, MITRE Corporation, some avionics manufacturers and individual pilots – cut the accident rate in the eastern part of Alaska by around 40%.

The airborne wind shear detection and alert system, fitted in an aircraft, detects and alerts the pilot both visually and aurally of a wind shear condition. In case of reactive wind shear detection system, the detection takes place when the aircraft penetrates a wind shear condition of sufficient force, which can pose a hazard to the aircraft. In case of predictive wind shear detection system, the detection takes place, if such wind shear condition is ahead of the aircraft. In 1988, the U.S. Federal Aviation Administration (FAA) mandated that all turbine-powered commercial aircraft must have on-board wind shear detection systems by 1993. Airlines successfully lobbied to have commercial turbo-prop aircraft exempted from this requirement.

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The Information Age is generally understood to have arrived with the Internet as it was developed through the 1970s and rolled out throughout the 1980s, and continues evolving to this day. So too the adoption of digital techniques in aviation also arrived progressively at around the same time and also continues today.