Automatic dependent surveillance-broadcast

Automatic dependent surveillance—broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation. 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 an element of the United States Next Generation Air Transportation System (NextGen), the Airports Authority of India upgrade plans in line with the ICAO Global Plan Initiatives and Aviation System Block Upgrade (ASBU), and the Single European Sky ATM Research project (SESAR). ADS–B equipment is mandatory for instrument flight rules (IFR) category aircraft in Australian airspace; the United States requires many aircraft (including all commercial passenger carriers) to be so equipped by January, 2020; and, the equipment has been mandatory for some aircraft in Europe since 2017. Canada is currently using ADS–B for limited air traffic control, mainly in the Hudson Bay area. ADS-B, which consists of two different services, 'ADS-B Out' and 'ADS-B In', could replace radar 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 (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 components aboard each aircraft: a high-integrity satellite navigation source (i.e. GPS or other certified GNSS 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 transponder, or at 978 MHz. The FAA would like to see aircraft that operate exclusively below 18,000 feet (5,500 m) 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 position source if one is not already present). ADS-B provides many benefits to both pilots and air traffic control that improve both the safety and efficiency of flight.