 A national plan for satellite navigation including implementation of technology demonstration system (TDS) over the Indian air space as a proof of concept had been prepared jointly by Airports Authority of India (AAI) and ISRO.TDS was successfully completed during 2007 by installing eight Indian Reference Stations (INRESs) at eight Indian airports and linked to the Master Control Center (MCC) located near Bangalore.Preliminary system acceptance testing has been successfully completed in December 2010.