Indian plan for Satellite-Based Navigation Systems for Civil Aviation

The Airports Authority of India and the Indian Space Research Organisation (ISRO) have signed a Memorandum of Understanding (MOU) to implement a satellite based navigation system as part of the satellite based Communication, Navigation, Surveillance (CNS) and Air Traffic Management (ATM) plan for Civil Aviation in India. For satellite based navigation in India two core constellations--Global Positioning System (GPS) of the United States and GLONASS of the Russian Federation--are available. The position accuracies achievable with these core constellations are not good enough for precision approach and landing requirements of Civil Aviation. These constellations need to be augmented. Three types of augmentation systems are possible - Ground Based Augmentation System (GBAS), Aircraft Based Augmentation Systems (ABAS) and Space Based Augmentation System (SBAS). ISRO will implement SBAS as a proof of concept. Named GAGAN, it will incorporate GPS augmented by a geosynchronous segment. This paper describes the Indian Plan for a Satellite Based Navigation System for Civil Aviation. A brief outline of the three segments - User Segment, Space Segment and Ground Segment necessary for implementation of an SBAS system over the Indian airspace is described. ACKNOWLEDGEMENTS The assistance rendered by Smt. Nalini R. Naik in preparing and typing the manuscript is gratefully acknowledged