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Eye in the sky to guide pilots

A revolution in India?s old ground-based navigation system is in the offing with the coming of the satellite-based system Gagan.

india Updated: Apr 29, 2006 02:56 IST

A revolution in India’s old ground-based navigation system is in the offing with the coming of the satellite-based system Gagan (GPS and Geo Augmented Navigation).

While aircraft movement over Indian airspace grows at the rate of 10-12 per cent annually, navigational aids continue to be ground-based and deficient. A big problem is that 55 per cent of Indian airspace is over water, where the ground-based system doesn't work.

According to SK Saraswati, executive director, communication, navigation and surveillance (planning), Airports Authority of India, aircraft navigate over oceanic airspace with the help of airborne autonomous facility/inertial navigation system even though their “reliability and accuracy isn’t very good”.

Another deficiency of the ground-based system is that it works on radio signals, which require a clear line of sight. AAI chairman K. Ramalingam told HT many of these problems would be solved with Gagan, which would be set up at a cost of Rs 600 crore. Gagan, prepared jointly by the Department of Space and AAI, will be ready for trial and initial operational phase by 2008.

As accuracy and reliability are critical, what is being planned is for Gagan to have ground-based reference stations to receive GPS data at different places. The data, co-related and corrected at a Master Station, will be sent through uplink station via ISRO satellite GSAT-4 -- expected to be launched in 2006 -- to the aircraft instantly for course correction.

According to Ramalingam, Gagan will introduce satellite-based navigation services in the Asia Pacific region, providing seamless navigation from east to west and vice versa, and bridging the gap between the European EGNOS and Japanese MSAS. It will be the fourth such system in the world after EGNOS, MSAS and the American WAAS.