ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)

EUROCONTROL in collaboration with various Air Navigation Service Providers (ANSPs) in Europe and in the United Kingdom established the CASCADE program to coordinate the implementation of Automatic Dependent Surveillance Broadcast (ADS-B) applications. In this program, the CRISTAL initiative provides data from validation trials in each country, to test the ADS-B technology in real scenarios where the operational needs exist. The ADS-B system is expected to play a key role to facilitate some of the safety-critical functions envisioned under the future operational concepts, including self-separation and Air Traffic Control based separation with reduced separation minima. ADS-B is a very complex system, highly dependent on the navigation and communication systems. A rigorous, clear and comprehensive assessment method is required to ensure that it is safe to operate in any particular context. This paper proposes a comprehensive framework to evaluate ADS-B data (obtained from NATS CRISTAL project) performance to assess whether it can meet the accuracy, latency and update rate requirements to support the above-mentioned safety-critical applications. In the proposed framework, Global Positioning System (GPS) data from aircraft navigation system are used as the reference data to validate ADS-B data accuracy as recorded by ground stations. The framework begins by decoding both sets of data (ADS-B and GPS) into the ASCII format. Both sets are then correlated based on the time and horizontal position, the most challenging task in the data evaluation process. A statistical evaluation is carried out in terms of accuracy, latency and update rate. The key challenges in this analysis and errors identified in each dataset are discussed in this paper.