Automatic Dependent Surveillance–Broadcast
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Automatic Dependent Surveillance–Broadcast (ADS-B) is a surveillance technology and form of Electronic Conspicuity in which an
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
determines its position via
satellite navigation A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by
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 airs ...
ground stations as a replacement for
secondary surveillance radar Secondary surveillance radar (SSR)''Secondary Surveillance Radar'', Stevens M.C. Artech House, is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the de ...
, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide
situational awareness Situational awareness or situation awareness (SA) is the perception of environmental elements and events with respect to time or space, the comprehension of their meaning, and the projection of their future status. An alternative definition is tha ...
and allow
self-separation Aircraft self-separation is the capability of an aircraft maintaining acceptably safe separation from other aircraft without following instructions or guidance from a referee agent for this purpose, such as air traffic control. In its simplest for ...
. ADS-B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system. ADS-B is being incorporated in various jurisdictions worldwide. It is an element of the United States Next Generation Air Transportation System (NextGen), the
Airports Authority of India The Airports Authority of India, or AAI, is a public sector enterprise under the ownership of the Ministry of Civil Aviation, Government of India. It is responsible for creating, upgrading, maintaining, and managing civil aviation infrastruct ...
upgrade plans in line with the
ICAO The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
Global Plan Initiatives and Aviation System Block Upgrade (ASBU), and the
Single European Sky ATM Research Single European Sky ATM Research (SESAR) is a collaborative project to completely overhaul European airspace and its air traffic management (ATM). The actual program is managed by the SESAR Joint Undertaking as a public–private partnership (PP ...
project (SESAR). ADS-B equipment is mandatory for
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) category aircraft in Australian airspace; the United States has required many aircraft (including all commercial passenger carriers and aircraft flying in areas that required a transponder) to be so equipped since January 2020; and, the equipment has been mandatory for some aircraft in Europe since 2017. Canada uses ADS-B for surveillance in remote regions not covered by traditional radar (areas around
Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...
, the
Labrador Sea The Labrador Sea (French: ''mer du Labrador'', Danish: ''Labradorhavet'') is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelf, continental shelves to the southwest, northwest, ...
,
Davis Strait Davis Strait is a northern arm of the Atlantic Ocean that lies north of the Labrador Sea. It lies between mid-western Greenland and Baffin Island in Nunavut, Canada. To the north is Baffin Bay. The strait was named for the English explorer Jo ...
,
Baffin Bay Baffin Bay ( Inuktitut: ''Saknirutiak Imanga''; kl, Avannaata Imaa; french: Baie de Baffin), located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arct ...
and southern
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
) since January 15, 2009. Aircraft operators are encouraged to install ADS-B products that are interoperable with US and European standards, and Canadian air traffic controllers can provide better and more fuel efficient flight routes when operators can be tracked via ADS-B.


Description

ADS-B, which consists of two different services, "ADS-B Out" and "ADS-B In", could replace
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
as the primary surveillance method for controlling aircraft worldwide. In the United States, ADS-B is an integral component of the NextGen national airspace strategy for upgrading and enhancing aviation infrastructure and operations. Also within the United States, the ADS-B system can provide traffic- and government-generated graphical weather information at no cost through TIS-B and FIS-B applications. ADS-B enhances safety by making an aircraft visible, realtime, to
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 airs ...
(ATC) and to other appropriately equipped ADS-B aircraft with position and velocity data transmitted every second. ADS-B data can be recorded and downloaded for post-flight analysis. ADS-B also provides the data infrastructure for inexpensive flight tracking, planning, and dispatch. Using "ADS-B Out", each aircraft periodically broadcasts information about itself, such as identification, current position, altitude and velocity, through an onboard transmitter. ADS-B Out provides air traffic controllers with real-time position information that is, in most cases, more accurate than the information available with current radar-based systems. With more accurate information, ATC will be able to position and separate aircraft with improved precision and timing. "ADS-B In" is the reception by aircraft of FIS-B and TIS-B data and other ADS-B data such as direct communication from nearby aircraft. The ground station broadcast data is typically only made available in the presence of an ADS-B Out broadcasting aircraft, limiting the usefulness of purely ADS-B In devices. The system relies on two
avionics Avionics (a blend word, blend of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, ...
components aboard each aircraft: a high-integrity
satellite navigation A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
source (i.e.
GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
or other certified
GNSS A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
receiver) and a datalink (the ADS-B unit). There are several types of certified ADS-B data links, but the most common ones operate at 1090 MHz, essentially a modified
Mode S The aviation transponder interrogation modes are the standard formats of pulsed sequences from an interrogating Secondary Surveillance Radar (SSR) or similar Automatic Dependent Surveillance-Broadcast (ADS-B) system. The reply format is usually refe ...
transponder, or at 978 MHz. The FAA would like to see aircraft that operate exclusively below use the 978 MHz link, as this will alleviate congestion of the 1090 MHz frequency. To obtain ADS-B Out capability at 1090 MHz, user-operators can install a new transponder or modify an existing transponder if the manufacturer offers an ADS-B upgrade (plus install a certified
GNSS A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
position source if one is not already present).


Benefits

ADS-B provides many benefits to both pilots and air traffic control that improve both the safety and efficiency of flight. When using an ''ADS-B In'' system, a pilot is able to view traffic information about surrounding aircraft if those aircraft are equipped with ADS-B Out. This information includes altitude, heading, speed, and distance to aircraft. In addition to receiving position reports from ADS-B Out participants, in the US, TIS-B can provide position reports on non ADS-B Out-equipped aircraft if suitable ground equipment and ground radar exist. ADS-R re-transmits ADS-B position reports between UAT and 1090 MHz frequency bands. Aircraft equipped with universal access transceiver (UAT) ''ADS-B In'' technology will be able to receive weather reports, and in the US, weather radar through flight information service-broadcast (FIS-B), which also transmits readable flight information such as
temporary flight restrictions The Federal Aviation Regulations (FARs) are rules prescribed by the Federal Aviation Administration (FAA) governing all aviation activities in the United States. The FARs comprise Title 14 of the Code of Federal Regulations (CFR). A wide variety ...
(TFRs) and
NOTAM A Notice to Airmen/Notice to Air Missions (NOTAM), is a notice filed with an aviation authority to alert aircraft pilots of potential hazards along a flight route or at a location that could affect the flight. NOTAMs are unclassified notices or ...
s. ADS-B ground stations are significantly cheaper to install and operate compared to primary and secondary radar systems used by air traffic control for aircraft separation and control. Unlike some alternative in-flight weather services currently being offered commercially, there will be no subscription fees to use ADS-B services or its various benefits in the US. The aircraft owner will pay for the equipment and installation, while the
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
(FAA) will pay for administering and broadcasting all the services related to the technology.


Safety

;Situational awareness ADS-B makes flying significantly safer for the aviation community by providing pilots with improved
situational awareness Situational awareness or situation awareness (SA) is the perception of environmental elements and events with respect to time or space, the comprehension of their meaning, and the projection of their future status. An alternative definition is tha ...
. Pilots in an ADS-B In equipped cockpit will have the ability to see, on their in-cockpit flight display, other traffic operating in the airspace as well as access to clear and detailed weather information. They will also be able to receive pertinent updates ranging from temporary flight restrictions to runway closings. ;Improved visibility Even aircraft only equipped with ADS-B Out will benefit from air traffic controllers' ability to more accurately and reliably monitor their position. When using this system both pilots and controllers will see the same radar picture. Other fully equipped aircraft using the airspace around them will be able to more easily identify and avoid conflict with an aircraft equipped with ADS-B Out. With past systems such as the Traffic alert and Collision Avoidance System (TCAS) aircraft could only see other aircraft equipped with the same technology. With ADS-B, information is sent to aircraft using ADS-B In, which displays all aircraft in the area, provided those aircraft are equipped with ADS-B Out. ADS-B provides better surveillance in fringe areas of radar coverage. ADS-B does not have the siting limitations of radar. Its accuracy is consistent throughout the range. In both forms of ADS-B (1090ES & 978 MHz UAT), the position report is updated once per second. The 978 MHz UAT provides the information in a single, short duration transmission. The 1090ES system transmits two different kinds of position reports (even/odd) randomly. To decode the position unambiguously, one position report of both kinds or a reference position nearby is needed. ADS-B enables improved safety by providing: * Radar-like
IFR 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 ...
separation in non-radar airspace * Increased VFR flight following coverage * ATC final approach and runway occupancy, reducing
runway incursion A runway incursion is an aviation incident involving improper positioning of vehicles or people on any airport runway or its protected area. When an incursion involves an ''active'' runway being used by arriving or departing aircraft, the pot ...
s on the ground * More accurate search and rescue response — although ADS-B can transmit "aircraft down" data, the FAA has stated that there is no intention to perform even a study of ADS-B's effectiveness in an "aircraft down" situation, simply based on the fact that ADS-B equipment has no requirement to be crashworthy, as compared to the current "black box" recorder. ADS-B was demonstrated to the
Civil Air Patrol Civil Air Patrol (CAP) is a congressionally chartered, federally supported non-profit corporation that serves as the official civilian auxiliary of the United States Air Force (USAF). CAP is a volunteer organization with an aviation-minded mem ...
(CAP) in March 2003 by
AOPA The Aircraft Owners and Pilots Association (AOPA) is a Frederick, Maryland-based American non-profit political organization that advocates for general aviation. AOPA's membership consists mainly of general aviation pilots in the United States ...
via flight demonstrations for possible integration of the technology in CAP activities. * Helps pilots to see and avoid other aircraft * Cockpit final approach and runway occupancy * Visual separation in VFR and MVFR conditions * VFR-like separation in all weather conditions * Real-time cockpit weather display * Real-time cockpit airspace display


Efficiency

;Reduced environmental impact ADS-B technology provides a more accurate report of an aircraft's position. This allows controllers to guide aircraft into and out of crowded airspace with smaller separation standards than it was previously possible to do safely. This reduces the amount of time aircraft must spend waiting for clearances, being vectored for spacing and holding. Estimates show that this is already having a beneficial impact by reducing pollution and fuel consumption. ;Traffic capacity improvement ADS-B enables increased capacity and efficiency by supporting: * Better ATC traffic flow management * Merging and spacing *
Self-separation Aircraft self-separation is the capability of an aircraft maintaining acceptably safe separation from other aircraft without following instructions or guidance from a referee agent for this purpose, such as air traffic control. In its simplest for ...
or station keeping * Enhanced visual approaches; * Closely spaced parallel approaches; * Reduced spacing on final approach; * Reduced aircraft separations; * Enhanced operations in high altitude airspace for the incremental evolution of the " free flight" concept; * Surface operations in lower visibility conditions; * Near visual meteorological conditions ( VMC) capacities throughout the airspace in most weather conditions; * Improved air traffic control services in non-radar airspace; * Trajectory-based operations providing a gently ascending and descending gradient with no step-downs or holding patterns needed. This will produce optimal trajectories with each aircraft becoming one node within a system wide information management network connecting all equipped parties in the air and on the ground. With all parties equipped with NextGen equipage, benefits will include reduced gate-to-gate travel times, increased runway utilization capacity, and increased efficiency with carbon conservation. * Use of ADS-B and CDTI may allow decreased approach spacing at certain airports to improve capacity during reduced-visibility operations when visual approach operations would normally be terminated (e.g., ceilings less than MVA +500).


Other applications

The ADS-B data link supports a number of airborne and ground applications. Each application has its own operational concepts, algorithms, procedures, standards, and user training. ;Cockpit display of traffic information A cockpit display of traffic information (CDTI) is a generic display that provides the flight crew with surveillance information about other aircraft, including their position. Traffic information for a CDTI may be obtained from one or multiple sources, including ADS-B, TCAS, and TIS-B. Direct air-to-air transmission of ADS-B messages supports display of proximate aircraft on a CDTI. In addition to traffic based on ADS-B reports, a CDTI function might also display current weather conditions, terrain, airspace structure, obstructions, detailed airport maps, and other information relevant to the particular phase of flight. ;Airborne collision avoidance ADS-B is seen as a valuable technology to enhance
airborne collision avoidance system An airborne collision avoidance system (ACAS, usually pronounced as ''ay-kas'') 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. ...
(ACAS) operation. Incorporation of ADS-B can provide benefits such as: * Decreasing the number of active interrogations required by ACAS, thus increasing effective range in high-density airspace. * Reducing unnecessary alarm rate by incorporating the ADS-B state vector, aircraft intent, and other information. * Use of the ACAS display as a CDTI, providing positive identification of traffic. * Extending collision avoidance below 1,000 feet above ground level, and detecting runway incursions. Eventually, the ACAS function may be provided based solely on ADS-B, without requiring active interrogations of other aircraft transponders. Other applications that may benefit from ADS-B include: * Lighting control automation and operation * Airport ground vehicle and aircraft rescue and firefighting vehicle operational needs * Altitude height keeping performance measurements *
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 ...
operations control * Conflict management * ATS conformance monitoring *
Aircraft spotting Aircraft spotting, or plane spotting is a hobby of tracking the movement of aircraft, which is often accomplished by photography. Besides monitoring aircraft, plane spotting enthusiasts (who are usually called plane spotters) also record informa ...
where personal receivers can be used to produce a virtual radar picture * A number of websites use
crowd-sourced Crowdsourcing involves a large group of dispersed participants contributing or producing goods or services—including ideas, votes, micro-tasks, and finances—for payment or as volunteers. Contemporary crowdsourcing often involves digita ...
distributed networks of ADS-B receivers to track air traffic.


Security risk

Aircraft with transponder only, or no transponder capability at all will not be shown. Pilots who become complacent or overconfident in this system are thus a safety problem, not only for themselves but for other transponder-only aircraft, and
glider aircraft A glider is a fixed-wing aircraft that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose free flight does not depend on an engine. Most gliders do not have an engine, although motor-gliders have ...
without ADS-B transponder. Glider aircraft often use the
FLARM FLARM is proprietary electronic system used to selectively alert pilots to potential collisions between aircraft. It is not formally an implementation of ADS-B, as it is optimized for the specific needs of light aircraft, not for long-range commun ...
system for collision avoidance with other glider aircraft, but this system is not compatible with ADS-B. Aircraft with ADS-B but without FLARM are thus a safety risk for gliders with FLARM but without ADS-B and vice versa. Some aircraft, like those used for towing gliders, have both FLARM and ADS-B transponders for this reason. A security researcher claimed in 2012 that ADS-B has no defence against being interfered with via spoofed ADS-B messages because they were neither
encrypted In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...
nor
authenticated Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicati ...
. The FAA responded to this criticism saying that they were aware of the issues and risks but were unable to disclose how they are mitigated as that is classified. A possible mitigation is
multilateration Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning). When more than three distances are involved, it may be called multilateration, for e ...
to verify that the claimed position is close to the position from which the message was broadcast. Here the timing of received messages is compared to establish distances from the antenna to the plane. The lack of any authentication within the standard makes it mandatory to validate any received data by use of the primary radar. Because the content of ADS-B messages is not encrypted, it may be read by anybody.


Theory of operation

The ADS-B system has three main components: 1) ground infrastructure, 2) airborne component, and 3) operating procedures. * A transmitting subsystem that includes message generation and transmission functions at the source; e.g., aircraft. * The transport protocol; e.g., VHF ( VDL mode 2 or 4), 1090ES, or 978 MHz UAT. * A receiving subsystem that includes message reception and report assembly functions at the receiving destination; e.g., other aircraft, vehicle or ground system. The source of the state vector and other transmitted information as well as user applications are not considered to be part of the ADS-B system.


Physical layer

Two link solutions are used as the physical layer for relaying ADS-B position reports: universal access transceiver, and 1090 MHz extended squitter.


Universal Access Transceiver (UAT)

A universal access transceiver is a
data link A data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a recei ...
intended to serve the majority of the
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 ...
community. The data link is approved in the
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
's "final rule" for use in all airspace except class A (above 18,000 ft. MSL). UAT is intended to support not only ADS-B, but also flight information service – broadcast (FIS-B), traffic information service – broadcast (TIS-B), and, if required in the future, supplementary ranging and positioning capabilities. Due to the set of standards required for this rule, it is seen as the most effective application for general aviation users. UAT will allow aircraft equipped with "out" broadcast capabilities to be seen by any other aircraft using ADS-B In technology as well as by FAA ground stations. Aircraft equipped with ADS-B In technology will be able to see detailed altitude and vector information from other ADS-B Out equipped aircraft as well as FIS-B and TIS-B broadcasts. The FIS-B broadcast will allow receiving aircraft to view weather and flight service information including
AIRMET An AIRMET, or Airmen's Meteorological Information, is a concise description of weather phenomena that are occurring or may occur (forecast) along an air route that may affect aircraft safety. Compared to SIGMETs, AIRMETs cover less severe weather: ...
s,
SIGMET SIGMET, or Significant Meteorological Information (AIM 7-1-6), is a severe weather advisory that contains meteorological information concerning the safety of all aircraft. Compared to AIRMETs, SIGMETs cover more severe weather. Types There a ...
s,
METAR METAR is a format for reporting weather information. A METAR weather report is predominantly used by aircraft pilots, and by meteorologists, who use aggregated METAR information to assist in weather forecasting. Raw METAR is the most common form ...
s, SPECI, national
NEXRAD NEXRAD or Nexrad (Next-Generation Radar) is a network of 160 high-resolution S-band Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United ...
, regional NEXRAD, D-NOTAMs, FDC-NOTAMs,
PIREP A pilot report or PIREP is a report of actual flight or ground conditions encountered by an aircraft. Reports commonly include information about atmospheric conditions (like temperature, icing, turbulence) or airport conditions (like runway con ...
s, special use airspace status, terminal area forecasts, amended terminal aerodrome forecasts (TAFs), and winds and temperatures aloft forecasts. These broadcasts serve to provide early adopters of the technology with benefits as an incentive for more pilots to use the technology before 2020. Aircraft receiving traffic information through the TIS-B service will see other aircraft in a manner that is similar to how all aircraft will be seen after they have equipped by 2020. The availability of a non-subscription weather information service, FIS-B, provides general aviation users with a useful alternative to other monthly or annual fee-based services. The UAT system is specifically designed for ADS-B operation. UAT is also the first link to be certified for "radar-like" ATC services in the United States. Since 2001 it has been providing en-route separation (the same as mosaic radar but not of single-site sensors) in Alaska. UAT is the only ADS-B link standard that is truly bidirectional: UAT users have access to ground-based aeronautical data (FIS-B) and can receive reports from proximate traffic (TIS-B) through a multilink gateway service that provides ADS-B reports for 1090ES-equipped aircraft and non-ADS-B equipped radar traffic. UAT equipped aircraft can also observe each other directly with high accuracy and minimal latency. Viable ADS-B UAT networks are being installed as part of the United States' NextGen air traffic system.


1090 MHz extended squitter

In 2002 the
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
(FAA) announced a dual link decision using the 1090 MHz extended squitter (1090 ES) link for air carrier and private or commercial operators of high-performance aircraft, and universal access transceiver link for the typical general aviation user. In November 2012, the
European Aviation Safety Agency The European Union Aviation Safety Agency (EASA) is an agency of the European Union (EU) with responsibility for civil aviation safety. It carries out certification, regulation and standardisation and also performs investigation and monitorin ...
confirmed that the European Union would also use 1090 ES for interoperability. The format of extended
squitter Squitter refers to random pulses, pulse-pairs and other non-solicited messages used in various aviation radio systems' signal maintenance. Squitter pulses were originally, and are still, used in the DME/TACAN air navigation systems. Squitter puls ...
messages has been codified by the ICAO. With 1090 ES, the existing
Mode S The aviation transponder interrogation modes are the standard formats of pulsed sequences from an interrogating Secondary Surveillance Radar (SSR) or similar Automatic Dependent Surveillance-Broadcast (ADS-B) system. The reply format is usually refe ...
transponder ( TSO C-112 or a standalone 1090 MHz
transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...
) supports a message type known as the extended squitter message. It is a periodic message that provides position, velocity, time, and, in the future, intent. The basic ES does not offer intent since current flight management systems do not provide such data (called trajectory change points). To enable an aircraft to send an extended squitter message, the transponder is modified (TSO C-166A) and aircraft position and other status information is routed to the transponder. ATC ground stations and aircraft equipped with traffic collision avoidance system (TCAS) already have the necessary 1090 MHz (Mode S) receivers to receive these signals, and would only require enhancements to accept and process the additional extended squitter information. As per the FAA ADS-B link decision, and the technical link standards, 1090 ES does not support FIS-B service.


Relationship to surveillance radar

Radar directly measures the range and bearing of an aircraft from a ground-based
antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...
. The primary surveillance radar is usually a pulse radar. It continuously transmits high power radio frequency (RF) pulses. Bearing is measured by the position of the rotating radar antenna when it receives the RF pulses that are reflected from the aircraft skin. Range is measured by measuring the time it takes for the RF energy to travel to and from the aircraft. Primary surveillance radar does not require any cooperation from the aircraft. It is robust in the sense that surveillance outage failure modes are limited to those associated with the ground radar system.
Secondary surveillance radar Secondary surveillance radar (SSR)''Secondary Surveillance Radar'', Stevens M.C. Artech House, is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the de ...
depends on active replies from the aircraft. Its failure modes include the
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 ...
aboard the aircraft. Typical ADS-B aircraft installations use the output of the navigation unit for navigation and for cooperative surveillance, introducing a common
failure mode Failure causes are defects in design, process, quality, or part application, which are the underlying cause of a failure or which initiate a process which leads to failure. Where failure depends on the user of the product or process, then human er ...
that must be accommodated in air traffic surveillance systems. The radiated beam becomes wider as the distance between the antenna and aircraft becomes greater, making the position information less accurate. Additionally, detecting changes in aircraft velocity requires several radar sweeps that are spaced several seconds apart. In contrast, a system using ADS-B creates and listens for periodic position and intent reports from aircraft. These reports are generated based on the aircraft's navigation system, and distributed via one or more of the ADS-B data links. The accuracy of the data is no longer susceptible to the position of the aircraft or the length of time between radar sweeps. (However, the signal strength of the signal received from the aircraft at the ground station is still dependent on the range from the aircraft to the receiver, and interference, obstacles, or weather could degrade the integrity of the received signal enough to prevent the digital data from being decoded without errors. When the aircraft is farther away, the weaker received signal will tend to be more affected by the aforementioned adverse factors and is less likely to be received without errors. Error detection will allow errors to be recognized, so the system maintains full accuracy regardless of aircraft position when the signal can be received and decoded correctly. This advantage does not equate to total indifference to the range of an aircraft from the ground station.) Today's
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 airs ...
(ATC) systems do not rely on coverage by a single radar. Instead a multiradar picture is presented via the ATC system's display to the
controller Controller may refer to: Occupations * Controller or financial controller, or in government accounting comptroller, a senior accounting position * Controller, someone who performs agent handling in espionage * Air traffic controller, a person ...
. This improves the quality of the reported position of the aircraft, provides a measure of redundancy, and makes it possible to verify the output of the different radars against others. This verification can also use sensor data from other technologies, such as ADS-B and
multilateration Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning). When more than three distances are involved, it may be called multilateration, for e ...
.


Relationship to ADS-A/ADS-C

There are two commonly recognized types of ADS for aircraft applications: * ADS-addressed (ADS-A), also known as ADS-Contract (ADS-C) * ADS-broadcast (ADS-B) ADS-A is based on a negotiated one-to-one peer relationship between an aircraft providing ADS information and a ground facility requiring receipt of ADS messages. For example, ADS-A reports are employed in the Future Air Navigation System (FANS) using the
Aircraft Communications Addressing and Reporting System In aviation, ACARS (; an acronym for Aircraft Communications Addressing and Reporting System) is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The protocol was de ...
(ACARS) as the communication protocol. During flight over areas without radar coverage, ''e.g.'', oceanic and polar, reports are periodically sent by an aircraft to the controlling air traffic region.


Traffic information service – broadcast (TIS–B)

Traffic information service – broadcast (TIS–B) supplements ADS-B's air-to-air services to provide complete situational awareness in the cockpit of all traffic known to the ATC system. TIS–B is an important service for an ADS-B link in airspace where not all aircraft are transmitting ADS-B information. The ground TIS–B station transmits surveillance target information on the ADS-B data link for unequipped targets or targets transmitting only on another ADS-B link. TIS–B uplinks are derived from the best available ground surveillance sources: * ground radars for primary and secondary targets * multilateration systems for targets on the airport surface * ADS-B systems for targets equipped with a different ADS-B link


Multilink gateway service

The multilink gateway service is a companion to TIS-B for achieving interoperability between different aircraft equipped with 1090ES or UAT by using ground-based relay stations. These aircraft cannot directly share air-to-air ADS-B data due to the different communication frequencies. In terminal areas, where both types of ADS-B link are in use, ADS-B/TIS-B ground stations use ground-to-air broadcasts to relay ADS-B reports received on one link to aircraft using the other link. Although multilink "solves" the issue of heavy airliners working on one frequency vs. light aircraft, the dual frequency nature of the system has several potential issues: * Since two aircraft on two different ADS-B frequencies must use a ground station to talk to each other, this introduces the ground station as a point of failure, although to be fair, the 1090 signal is dependent secondary radar scans in any case (and thus cannot operate without a ground station). * The time taken to traverse the full path from one aircraft, to the ground station, then to the second aircraft adds delay to the signal. This contrasts with two autonomous ADS-B transceivers on UAT, which have a shorter and shorter delay as they converge. * Aircraft are frequently out of the range of ground based radar due to altitude. Radar can be blocked by mountains, and typically is not useful for coverage near an airport unless that airport has radar. Thus, approach, departure, and especially taxi/ground based operations are compromised (a major selling point of the system). Because of the issues with multilink, many ADS-B manufacturers are designing ADS-B systems as dual-frequency capable.


Flight information services-broadcast (FIS-B)

FIS-B provides weather text, weather graphics, NOTAMs, ATIS, and similar information. FIS-B is inherently different from ADS-B in that it requires sources of data external to the aircraft or broadcasting unit, and has different performance requirements such as periodicity of broadcast. In the United States, FIS-B services are provided over the UAT link in areas that have a ground surveillance infrastructure. Another potential aircraft-based broadcast capability is to transmit aircraft measurements of meteorological data.


Implementations by country


Australia

Australia has full continental ADS-B coverage above FL300 (30,000 feet). ADS-B equipment is mandatory for all aircraft flying at this altitude. To achieve this level of coverage Airservices Australia operates more than 70 ADS-B ground receiver sites. In Australia the aviation regulator, the Civil Aviation Safety Authority, mandated a phased requirement for all Instrument Flight Rules (IFR) aircraft to be equipped with ADS-B Out by 2 February 2017. This applies to all Australian aircraft.


Canada

Nav Canada Nav Canada (styled as NAV CANADA) is a privately run, not-for-profit corporation that owns and operates Canada's civil air navigation system (ANS). It was established in accordance with the ''Civil Air Navigation Services Commercialization Act ...
commissioned operational use of ADS-B in 2009 and is now using it to provide coverage of its northern airspace around
Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...
, most of which currently has no radar coverage. The service was then extended to cover some oceanic areas off the east coast of Canada including the
Labrador Sea The Labrador Sea (French: ''mer du Labrador'', Danish: ''Labradorhavet'') is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelf, continental shelves to the southwest, northwest, ...
,
Davis Strait Davis Strait is a northern arm of the Atlantic Ocean that lies north of the Labrador Sea. It lies between mid-western Greenland and Baffin Island in Nunavut, Canada. To the north is Baffin Bay. The strait was named for the English explorer Jo ...
,
Baffin Bay Baffin Bay ( Inuktitut: ''Saknirutiak Imanga''; kl, Avannaata Imaa; french: Baie de Baffin), located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arct ...
, and part of the
North Atlantic Tracks North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), is a structured set of transatlantic flight routes that stretch from the eastern North America to western Europe across the Atlantic Ocean, within the ...
around southern
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
. The service is expected to be later extended to cover the rest of the Canadian Arctic, and to the rest of Canada. In 2018, Nav Canada issued an aeronautical study proposing a mandate for Aireon-compatible ADS-B Out for all aircraft in Class A Airspace by 2021 and Class B Airspace by 2022, requiring a transponder capable of delivering antenna diversity performance. In response to stakeholder feedback, Nav Canada later announced that such equipment will not be mandated according to that timeline, but rather that suitably equipped aircraft would be handled on a priority basis. The dates upon which equipment will be required for operation in Canadian airspace have been announced as August 10, 2023 for Class A Airspace, May 16 2024 for Class B Airspace and Class C,D and E no sooner than 2026. In May 2021, the not-for-profi
Canadian In-Flight Information Broadcasting Association
announced its intention to build and operate a network broadcasting FIS-B (weather) and TIS-B (traffic) information on 978 MHz. By spring 2022, five ground stations were operating in Ontario, with several more stations planned for Alberta and Saskatchewan. The Canadian network is fully compatible with the United States network. Aircraft can use the same ADS-B In receivers in both countries and the provided services operate seamlessly when crossing the border. CIFIB plans to have about 100 stations operating within a few years. Coverage in Canada will not be coast-to-coast, but will focus on areas with higher traffic.


China

An American company ADS-B Technologies created one of the largest and most successful ADS-B systems in the world (an eight-station, 350+ aircraft network that spans more than 1,200  nmi across Central China). This was also the first UAT installation outside the United States. As of March 2009, more than 1.2 million incident/failure free flight hours have been flown with these ADS-B systems.


Iceland

As of 2010, Isavia is in the process of installing ADS-B across the North Atlantic Ocean. The system is made up by 18 ADS-B receiver stations in
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...
,
Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...
, and
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
.


India

The Airports Authority of India (AAI), which manages the country's airspace, first commissioned German company Comsoft to install ADS-B ground stations at 14 airport sites nationwide in 2012. Comsoft finished installing seven new ADS-B ground stations under a second phase of deployment which India subsequently integrated into its ATC system in 2014, thus completing its ground network for automatic dependent surveillance-broadcast (ADS-B) tracking of aircraft. In line with the International Civil Aviation Organization's aviation system block upgrade plan, AAI has said that its ADS-B network will provide redundant, satellite-based surveillance where radar coverage exists, fill gaps in surveillance where radar coverage is not possible due to high terrain or remote airspace and enable it to share ADS-B data with neighboring countries. The network covers the Indian subcontinent, plus parts of the Bay of Bengal and the Arabian Sea.


Sweden

LFV Group in Sweden has implemented a nationwide ADS-B network with 12 ground stations. Installation commenced during spring 2006, and the network was fully (technically) operational in 2007. An ADS-B–supported system is planned for operational usage in
Kiruna (; se, Giron ; fi, Kiiruna ) is the northernmost Stad (Sweden), city in Sweden, situated in the province of Lapland, Sweden, Lapland. It had 17,002 inhabitants in 2016 and is the seat of Kiruna Municipality (population: 23,167 in 2016) in Norr ...
, Sweden, during spring 2009. Based on the VDL Mode 4 standards, the network of ground stations can support services for ADS-B, TIS-B, FIS-B, GNS-B (DGNSS augmentation) and point-to-point communication, allowing aircraft equipped with VDL 4-compliant transceivers to lower fuel consumption and reduce flight times.


United Arab Emirates

United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia (The Middle East). It is located at th ...
commissioned three operational redundant ADS-B ground stations in early 2009 and is now using ADS-B to provide enhanced coverage of its upper airspace in combination and integrated with conventional surveillance radars.


United States

To reduce congestion and cope with growing aircraft traffic, the
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
has been developing the Next-Generation Air Transportation System (NextGen), including ADS-B. ADS-B equipment is built to meet one of two sets of industry standards, DO-260B and DO-282B. Aircraft operating in the United States in the airspace classes listed below are required to carry equipment that produces an ADS-B Out broadcast. ADS-B Out broadcasts information about an aircraft through an onboard transmitter to a ground receiver, moving air traffic control from a radar-based system to a satellite-derived aircraft location system. There is no such mandate for ADS-B In, which receives data and provides it to in-cockpit displays. The FAA airspace requirements intentionally exclude some airspace that is frequently used by general aviation. Operators can choose the 1090 megahertz extended squitter broadcast link, or the universal access transceiver broadcast link. FAA did not adopt higher performance standards that would enable all of the initial ADS-B In applications, but these can optionally be adopted.


Equipping aircraft

Fleet: 250,000 GA aircraft that will need ADS-B by 2020 of which 165,000 aircraft subject to ADS-B Out (Class I and Class II aircraft that generally fly below 18 000 feet). FAA forecasts an increase in the GA fleet from 224,172 aircraft in 2010 to 270,920 aircraft in 2031, growing an average of 0.9% per year.


Funding resources

Recent (April 2011) US federal legislation via House Bill for FAA re-authorization permits an "equipping fund" that includes a portion for some general aviation aircraft. The fund would provide financing at competitive rates backed by
loan guarantee A loan guarantee, in finance, is a promise by one party (the guarantor) to assume the debt obligation of a borrower if that borrower defaults. A guarantee can be limited or unlimited, making the guarantor liable for only a portion or all of the d ...
s. A public-private partnership has been formed as the NextGen Equipage Fund, LLC which is managed by NEXA Capital Partners, LLC.


US implementation timetable

The Federal Aviation Administration ADS-B implementation is broken into three segments each with a corresponding time line.
Ground segment A ground segment consists of all the ground-based elements of a space system used by operators and support personnel, as opposed to the space segment and user segment. The ground segment enables management of a spacecraft, and distribution of p ...
implementation and deployment is expected to begin in 2009 and be completed by 2013 throughout the
National Airspace System The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components ...
(NAS). Airborne equipment is user-driven and is expected to be completed both voluntarily based on perceived benefits and through regulatory actions (Rulemaking) by the FAA. The cost to equip with ADS-B Out capability is relatively small and would benefit the airspace with surveillance in areas not currently served by radar. The FAA intends to provide similar service within the NAS to what radar is currently providing (5  nmi en route and 3 nmi terminal radar standards) as a first step to implementation. However, ADS-B In capability is viewed as the most likely way to improve NAS throughput and enhance capacity. In December 2008, Acting FAA Administrator Robert A. Sturgell gave the go-ahead for ADS-B to go live in southern Florida. The south Florida installation, which consists of 11 ground stations and supporting equipment, is the first commissioned in the United States, although developmental systems have been online in Alaska, Arizona, and along the East Coast since 2004. The completed system will consist of 794 ground station transceivers. The December 2008 action is in compliance with a late-term
executive order In the United States, an executive order is a directive by the president of the United States that manages operations of the federal government. The legal or constitutional basis for executive orders has multiple sources. Article Two of t ...
from
George W. Bush George Walker Bush (born July 6, 1946) is an American politician who served as the 43rd president of the United States from 2001 to 2009. A member of the Republican Party, Bush family, and son of the 41st president George H. W. Bush, he ...
which mandated accelerated approval of NextGen.


=FAA segment 1 (2006–09)

= ADS-B deployment and voluntary equipment, along with rule-making activities. Pockets of development will exploit equipment deployment in the areas that will provide proof of concept for integration to ATC automation systems deployed in the NAS. It is being developed at the FAA's
William J. Hughes Technical Center The FAA William J. Hughes Technical Center is an aviation research and development, and test and evaluation facility. The Technical Center serves as the national scientific test base for the Federal Aviation Administration. Technical Center progr ...
near
Egg Harbor City, New Jersey Egg Harbor City is a City (New Jersey), city in Atlantic County, New Jersey, Atlantic County, New Jersey, United States. As of the 2020 United States Census, the city's population was 4,396, an increase of 153 from the 2010 Census.
.


=FAA segment 2 (2010–14)

= ADS-B ground stations will be deployed throughout the NAS, with an in-service decision due in the 2012–2013 time frame. Completed deployment will occur in 2013–14. Equipment rules have been finalized and the current standards are DO-282B for UAT and DO-260B for 1090ES: * Airport situational awareness — a combination of detailed airport maps, airport multilateration systems, ADS-B systems and enhanced aircraft displays have the potential to significantly improve Airport Surface Situational Awareness (ASSA), and Final Approach and Runway Occupancy Awareness (FAROA). * Oceanic In-trail — ADS-B may provide enhanced situational awareness and safety for Oceanic In-trail maneuvers as additional aircraft become equipped. * Gulf of Mexico — in the Gulf of Mexico, where ATC radar coverage is incomplete, the FAA is locating ADS-B (1090 MHz) receivers on oil rigs to relay information received from aircraft equipped with ADS-B extended squitters back to the Houston Center to expand and improve surveillance coverage. * Terminal Airspace — ADS-B is currently in service for two terminal airspace areas,
Louisville, Kentucky Louisville ( , , ) is the largest city in the Commonwealth of Kentucky and the 28th most-populous city in the United States. Louisville is the historical seat and, since 2003, the nominal seat of Jefferson County, on the Indiana border ...
, and
Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
, Pennsylvania.


=FAA segment 3 (2015–20)

= ADS-B In equipment will be based on user perceived benefit, but is expected to be providing increased situational awareness and efficiency benefits within this segment. Those aircraft who choose to equip in advance of any mandate will see benefits associated with preferential routes and specific applications. Limited radar decommissioning will begin in the time frame with an ultimate goal of a 50% reduction in the secondary surveillance radar infrastructure. On 27 May 2010, the FAA published its final rule mandating that by 2020 all aircraft owners will be required to have ADS-B Out capabilities when operating in any airspace that currently requires a transponder (
airspace classes The world's navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the International Civil Aviation Organization (ICAO) and described be ...
A, B, and C, and airspace class E at certain altitudes). On 14 June 2012, FreeFlight Systems and
Chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock ...
received STC for first rule-compliant ADS-B installation in GOMEX helicopters that was awarded by the FAA.


Early adopters

*Cargo Airline Association — Cargo carriers, notably
UPS UPS or ups may refer to: Companies and organizations * United Parcel Service, an American shipping company ** The UPS Store, UPS subsidiary ** UPS Airlines, UPS subsidiary * Underground Press Syndicate, later ''Alternative Press Syndicate'' or ...
. They operate at their hub airports largely at night. Much of the benefit to these carriers is envisioned through merging and spacing the arriving and departing traffic to a more manageable flow. More environmentally friendly and efficient
area navigation Area navigation (RNAV, usually pronounced as "''ar-nav"'') is a method of instrument flight rules (IFR) navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigate directly to and from t ...
(RNAV) descent profiles, combined with CDTI, may allow crews to eventually aid controllers with assisted visual acquisition of traffic and limited cockpit-based separation of aircraft. The benefits to the carrier are fuel and time efficiencies associated with idle descent and shorter traffic patterns than typical radar vectoring allows. *Embry-Riddle Aeronautical University — ERAU has equipped their training aircraft at its two main campuses in Florida and Arizona with UAT ADS-B capability as a situational safety enhancement. The University has been doing this since May 2003, making it the first use in general aviation. With the addition of the Garmin G1000 flight instrument system to their fleet in 2006, ERAU became the first fleet to combine a glass cockpit with ADS-B. *University of North Dakota — UND has received an FAA grant to test ADS-B, and has begun to outfit their Piper Warrior fleet with an ADS-B package.


Privacy

The FAA in America has come up with two system to address privacy concerns * Limiting Aircraft Data Displayed (LADD): Aircraft owners or designated representatives may request limiting aircraft data displayed (formally referred to as blocking) or unblocking of flight tracking data. Flight tracking services that draw the data from FAA agree to block the information. * Privacy ICAO Aircraft (PIA): Program to improve the privacy of eligible aircraft by enabling aircraft owners to request an alternate, temporary ICAO aircraft address, which will not be assigned to the owner in the Civil Aviation Registry (CAR).


System design considerations

A concern for any ADS-B protocol is the capacity for carrying ADS-B messages from aircraft, as well as allowing the radio channel to continue to support any legacy services. For 1090 ES, each ADS-B message is composed of a pair of data packets. The greater the number of packets transmitted from one aircraft, the fewer aircraft that can participate in the system, due to the fixed and limited channel data Bandwidth (signal processing), bandwidth. System capacity is defined by establishing a criterion for what the worst environment is likely to be, then making that a minimum requirement for system capacity. For 1090 ES, both TCAS and ATCRBS/Secondary surveillance radar, MSSR are existing users of the channel. 1090 ES ADS-B must not reduce capacity of these existing systems. The FAA national program office and other international aviation regulators are addressing concerns about ADS-B non-secure nature of ADS-B transmissions. ADS-B messages can be used to know the location of an aircraft, and there is no means to guarantee that this information is not used inappropriately. Additionally, there are some concerns about the integrity of ADS-B transmissions. ADS-B messages can be produced, with simple, low-cost measures, which spoof the locations of multiple phantom aircraft to disrupt safe air travel. There is no foolproof means to guarantee integrity, but there are means to monitor for this type of activity. This problem is however similar to the usage of ATCRBS/MSSR where false signals also are potentially dangerous (uncorrelated secondary tracks). There are some concerns about ADS-B dependence on Global navigation satellite system, satellite navigation systems to generate state vector information, although the risks can be mitigated by using redundant sources of state vector information; e.g., Global Positioning System, GPS, GLONASS, Galileo (satellite navigation), Galileo or
multilateration Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning). When more than three distances are involved, it may be called multilateration, for e ...
. There are some general aviation concerns that ADS-B removes anonymity of the VFR aircraft operations. The ICAO 24-bit
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 ...
code specifically assigned to each aircraft will allow monitoring of that aircraft when within the service volumes of the Mode-S/ADS-B system. Unlike the Mode A/C transponders, there is no code "1200"/"7000", which offers casual anonymity. Mode-S/ADS-B identifies the aircraft uniquely among all in the world, in a similar fashion as a MAC address, MAC number for an Ethernet card or the International Mobile Equipment Identity (IMEI) of a GSM phone. However, the FAA is allowing UAT-equipped aircraft to utilize a random self-assigned temporary ICAO address in conjunction with the use of beacon code 1200. 1090 ES equipped aircraft using ADS-B will not have this option. In order for the ADS-B system to function to the fullest extent, equipage into all aircraft in the airspace is required. This demands the transponder technology be scalable from the smallest aircraft to the largest aircraft to allow for 100% equipage for any given airspace. Current transponder technology is capable of equipping the larger, traditional aircraft but a new type of transponder is required for equipping into aircraft that are smaller and lighter or don't have electrical systems like the large traditionally transponder equipped aircraft. The requirements for these smaller and lighter aircraft are mainly size, weight, and power (SWAP) and transponder technology must allow for equipage of these types of aircraft to enable saturation of ADS-B for total visibility in any given airspace. On 7 June 2002 the FAA published a historical overview of its decision on the ADS-B link architecture for use in the
National Airspace System The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components ...
(NAS).


Technical and regulatory documents

* ''Minimum Aviation System Performance Standards'' (MASPS) * ''Minimum Operational Performance Standards'' (MOPS) * DO-242A — ADS-B MASPS. Describes system-wide operational use of ADS-B.


Satellite (space based) ADS-B Collection

A significant step forward for ADS-B is the reception by artificial satellites of the ADS-B signal. It was tested for the first time in 2013 on ESA's PROBA-V and it is being deployed by companies like Spire Global using low-cost nanosatellites. Aireon is also working on space-based ADS-B with the Iridium satellite constellation, Iridium satellite network, a LEO (Low Earth Orbit) satellite network that was originally created to deliver phone and data service anywhere on the planet. By capturing ADS-B position data from aircraft flying below the satellite, the network will give the following capabilities: * Air traffic control using surveillance based separation standards will be possible over water, in areas that radar does not currently cover. Currently, air traffic control uses the larger procedural separation standard in oceanic and remote areas. * As is currently possible in radar covered areas, a position history will be available for lost aircraft, as in the case of Malaysia Airlines Flight 370. The system only receives ADS-B on aircraft broadcasting on the 1090 MHz frequency. This limits the system generally to airliners and business aircraft, despite the fact that small aircraft are frequently off radar due to mountains blocking the signal at low altitudes. The system could be compromised by smaller, private aircraft with exclusively belly mounted ADS-B antennas, due to the aircraft hull blocking the signal. The rationale for using the Iridium satellite network for this new capability was due to: * The Iridium satellites fly very low, and thus can receive the ADS-B out signals more reliably (transponders and ADS-B were designed for ground reception). * Iridium satellites are replaced relatively frequently due to the increased air friction at their lower altitude, and thus lower lifespan. Thus the system would be deployed on iridium faster. * Iridium provides worldwide coverage, including the poles. In September 2016, Aireon and FlightAware announced a partnership to provide this global space-based ADS-B data to airlines for flight tracking of their fleets and, in response to Malaysia Airlines Flight 370, for compliance with the ICAO Global Aeronautical Distress and Safety System (GADSS) requirement for airlines to track their fleets. In December 2016, Flightradar24 entered an agreement with Gomspace for space-based tracking in 2016. SpaceX subsequently placed 66 operational and 9 spare Iridium satellites in orbit over the course of 8 launches between 14 January 2017 and 11 January 2019. Another 6 spare satellites remain on the ground. The
ICAO The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...
describes space-based ADS-B as a technology equalizer, offering developing nations an Air traffic control radar beacon system, airspace surveillance capability. By 2020, 34 nations will deploy the system, including the 17 members of the Agency for Aerial Navigation Safety in Africa and Madagascar, Asecna in Africa, and the Corporación Centroamericana de Servicios de Navegación Aérea, Cocesna air navigation services agency in Central America. More frequent updates in the
North Atlantic Tracks North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), is a structured set of transatlantic flight routes that stretch from the eastern North America to western Europe across the Atlantic Ocean, within the ...
allowed reducing longitudinal Separation (aeronautics), separation from and lateral separations from . The FAA plans an evaluation in the Caribbean airspace from March 2020 until 2021, to complement the unreliable Grand Turk Island radar which allow reducing separation from .


See also

* Acronyms and abbreviations in avionics * ASDE-X * Automatic Identification System, a conceptually similar system for marine vessels * Advanced Train Control System, a conceptually similar system for railroads * Automatic Packet Reporting System (APRS), a conceptually similar GPS-based tracking system in the amateur radio service * DO-212, minimal operational performance standards for airborne automatic surveillance (ADS) * Eurocat (air traffic control) *
FLARM FLARM is proprietary electronic system used to selectively alert pilots to potential collisions between aircraft. It is not formally an implementation of ADS-B, as it is optimized for the specific needs of light aircraft, not for long-range commun ...
* Flight tracking * Free flight (air traffic control) * GPS aircraft tracking * Portable collision avoidance system * Traffic collision avoidance system


References


Further reading

*


External links

* * * * *
ADS-B Monitor
- a free tool to decode, display and log ADS-B messages {{DEFAULTSORT:Automatic Dependent Surveillance-Broadcast Avionics Air traffic control