ADS-B Features and Capabilities
Tracking more aircraft, more accurately.
The technology at the heart of NextGen is Automatic Dependent Surveillance-Broadcast (ADS-B). Essentially it's a technology solution that pinpoints an aircraft's location using satellite GPS navigation, and allows the aircraft to constantly broadcast its precise location and other flight data (e.g., altitude, velocity) to nearby aircraft and air traffic controllers. ADS-B will for the first time allow both pilots and controllers to see the same real-time displays of air traffic, thus improving safety and air traffic management.
ADS-B stands for:
• Automatic It's always on and requires no operator intervention.
• Dependent It depends on an accurate Global Navigation Satellite System (GNSS) signal or a Flight Management System (FMS) for positional data.
• Surveillance It provides "radar-like" surveillance services to determine the position of an aircraft.
• Broadcast It continuously broadcasts aircraft position and other data to any properly equipped aircraft and ground station.
The benefits of ADS-B
ADS-B is a vital element of a modernized air transportation system.
• Lower Cost, Higher Accuracy, and More Frequent Updating of Information ADS-B infrastructure consists of relatively simple radio stations, which are significantly cheaper to install and maintain than traditional radar that requires significant mechanical infrastructure and signal processing. ADS-B is also more accurate at identifying aircraft and determining position. The ADS-B System is updated by aircraft every second, compared to once every 12 seconds for en route radar systems. And ADS-B provides three-meter accuracy, which combines for increased operating efficiency in areas of dense traffic.
• Full Airspace Coverage ADS-B equipment can be installed in areas where it is not feasible to establish radar-based surveillance equipment. For instance, ADS-B equipment will be installed on oil platforms in the Gulf of Mexico, delivering substantial safety and efficiency benefits to air traffic flying over the area.
• Improved Cockpit Safety ADS-B equipped aircraft will be able to receive and display in the cockpit the position of all other ADS-B equipped aircraft in the area. Until all aircraft can be fully equipped, the Traffic Information Services Broadcasts (TIS-B) will provide situational awareness to ADS-B equipped aircraft by identifying radar targets of non ADS-B equipped aircraft. The FAA's ADS-B concept also provides Flight Information Service - Broadcast (FIS-B) to provide pilots with current weather information and awareness of meteorological conditions that might impact flight.
• Increased Airspace Capacity and Efficiency ADS-B provides a vehicle for increase cockpit involvement in the air traffic control process. This may represent the most significant potential benefit of ADS-B in terms of airspace capacity and efficiency. The ability of aircraft to have a cockpit display of all surrounding traffic enables air traffic control procedures that begin to involve the participation of the cockpit crew. Several applications of this capability have been defined and are in the process of achieving operational certification. For instance, Cockpit Based Merging and Spacing can allow a pilot to lock onto a proceeding aircraft and to maintain a very precise spacing interval. This offers the ability to optimize the arrival spacing at busy terminal areas and to make maximum use of Continuous Descent Arrival (CDA) arrival procedures delivering fuel savings and reduced emissions.
|On the ground, dependent on human participation
||On the aircraft, providing a constant flowof more accurate ID and location data|
|Coverage gaps exist in some areas
||ADS-B ground stations can be placed anywhere (e.g. mountains, oil rigs)|
|Positions updated by aircraft every 12 seconds
||Positions updated by aircraft every second|
|Costly to install and maintain
||Significantly less costly to install and maintain|
Broadcast and surveillance services
The FAA's implementation of ADS-B will provide four broadcast and surveillance services.
ADS-B. The first service within the broad ADS-B concept is ADS-B itself. This service involves the broadcast by aircraft of ADS-B messages, the receipt of these messages by airborne aircraft, and the collection of the messages by the ground radio infrastructure for the delivery of the data to the air traffic control facilities for ATC purposes.
ADS-R Automatic Dependant Surveillance-Rebroadcast accommodates the dual link nature of ADS-B, which broadcasts on both 1090 MHz-for air transport, military and high-end general aviation aircraft-and the Universal Access Transceiver (UAT)-for lower cost airborne avionics on aircraft flying below 24,000 feet. ADS-R will translate all 1090 MHz messages and re-transmit them in UAT format, and vice versa. Therefore, ADS-R assures that UAT and 1090 MHz aircraft will see each other.
The two services, ADS-B and ADS-R are collectively referred to as "surveillance services" and are categorized as "critical services" by the FAA for ATC purposes.
TIS-B Traffic Information Service—Broadcast. Under this service the ground infrastructure ingests all FAA radar-based surveillance data for any targets that are not ADS-B equipped and broadcasts the ADS-B message on both the 1090 MHz and UAT links. This gives airborne aircraft unprecedented situational awareness by displaying data on all airborne aircraft in its proximity on a cockpit display.
FIS-B Flight Information Service—Broadcast. Under this service the ground infrastructure ingests weather and aeronautical data and broadcasts on the UAT link, so pilots have an understanding of all weather and aviation system changes that might impact flight.
The combination of TIS-B and FIS-B uplink services are referred to as "broadcast services" and are categorized as "essential services" by the FAA for ATC purposes. Critical services have higher availability requirements than essential services because they will be used by ATC to separate aircraft.