Automatic Dependent Surveillance Broadcast (ADS-B) System

Automatic Dependent Surveillance Broadcast (ADS-B)  image download

Automatic Dependent Surveillance Broadcast

The ADS-B Collision Avoidance System is a significant part of the Regulatory Authorities's NextGen plan to transform the airspace system globally. In view of the increasing number of aircraft using the same airspace and ground facilities at the same time, it requires the implementation of new technologies to maintain a high level of performance and safety to ensure the safe operation of each aircraft with adequate separation and zero tolerance. The development of this new collision avoidance system known as Automatic Dependent Surveillance Broadcast (ADS-B) has resulted from the successful deployment of global navigation satellite systems (GNSS), such as GPS (Global Positioning System). ADS-B is an integral part of the NextGen program. The implementation of its ground and airborne infrastructure is currently underway all over the world. Some airspace has already implemented the programme. Aircraft manufacturers already started producing modern aircraft with the incorporation of this new technology, ADS-B.

ADS-B Modes

The ADS-B has two segments that is ADS-B OUT & ADS-B IN.

The transmission of ADS-B information from an aircraft is known as ADS-B OUT and the receipt of ADS-B information by an aircraft is known as ADS-B IN.


ADS-B OUT combines the positional data provided by a GPS sensor with on-board flight status information of an aircraft, including as location, altitude, velocity, and time. This information is then sent to other ADS-B enabled aircraft and ground stations.

Two different frequencies are used to carry these ADS-B broadcasts with data link capability. The first frequency is an expanded use of 1090 MHz Mode-S transponder protocol system known as 1090 ES. The second frequency is 978 MHz, largely being introduced as a new broadband solution for use of general aviation implementation of ADS-B. A 978 Universal Access Transceiver (UAT) is used to accomplish this in USA. An Omni-directional antenna, GPS antenna and receiver is required for ADS-B operation. Airborne receivers of an ADS-B broadcast utilise the data to depict the transmitting aircraft's location and movement on a flight deck display similar to TCAS.


ADS-B IN offers features not available in TCAS equipped aircraft. The ADS-B equipped aircraft are able to receive several useful data to enhance situational awareness. On a distinct frequency, traffic information services-broadcast (TIS-B) provide traffic information from non-ADS-B and ADS-B aircraft. Any traffic data in the linked network of ground stations, as well as ground radar monitoring of surface targets, is supplied immediately to the flight deck of an aircraft via ADS-B IN. This gives a more complete view than just avoiding collisions between planes. The Flight Information Services-Broadcast (FIS-B) are also received by ADS-B IN system. Weather text and graphics, ATIS information, and NOTAMS are able to be received in aircraft that have 987 UAT capabilities.

 Advantage of ADS-B

The ADS-B ground stations are less expensive than conventional radar and are constructed in remote and obstructed areas to proliferate ADS-B. ADS-B Ground stations in the Air Traffic Management System communicate information from airborne ADS-B broadcasts with other ground stations (ATMS). There is no requirement for human confirmation when data is sent. The network is connected by microwave and satellite transmissions.

For efficiently traffic separation and control with less error, ADS-B has many advantages over conventional ground-based radar used at present. The first advantage is the entire airspace can be covered with a much lower expense. The existing old ATC radar system that is in place is expensive to maintain and replace. Additionally, these old Radar are consuming more power in compared to ADS-B ground station Antenna. Furthermore, because the vector state is generated by the aircraft with the support of GPS satellites, ADS-B offers more accurate information. Weather is a greatly reduced factor with ADS-B. Ultra-high frequency GPS transmissions are not affected. Increased positioning precision enables for higher density traffic flow and landing approaches, which is a clear requirement when operating more planes in and out of the same number of terminals. The increased level of control also allows for better weather routing and optimal fuel burn rates. Collision avoidance is extended to cover runway incursion by other aircraft and support vehicles operating on the airport's surface.

Testing & Maintenance of ADS-B

ADS-B test units are available for skilled maintenance staff to use to ensure that ADS-B equipment is working properly. This is crucial because reliable data from each aircraft and throughout the ADS-B system is required for close tolerance air traffic separation.

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