The Airports Authority of India, or AAI, is a public sector enterprise under the ownership of the Ministry of Civil Aviation, Government of India. It is responsible for creating, upgrading, maintaining, and managing civil aviation infrastructure in India. It provides Communication Navigation Surveillance/Air Traffic Management (CNS/ATM) services over the Indian airspace and adjoining oceanic areas. AAI currently manages a total of 137 airports, including 34 international airports, 10 Customs Airports, 81 domestic airports, and 23 Civil enclaves at Defense airfields. AAI also has ground installations at all airports and 25 other locations to ensure the safety of aircraft operations. AAI covers all major air routes over the Indian landmass via 29 Radar installations at 11 locations along with 700 VOR/DVOR installations co-located with Distance Measuring Equipment (DME). 52 runways are provided with Instrument landing system (ILS) installations with Night Landing Facilities at most of these airports and an Automatic Message Switching System at 15 Airports. From Wikipedia
