GPS Aided Geo Augmented Navigation (GAGAN) was started by the Indian Union Minister for Civil Aviation, Praful Patel . GAGAN is Satellite Based Navigation System (SBNS) used to Provide Satellite Based Augmentation System Services over India and neighboring regions. GAGAN will provide seamless coverage of air traffic from south Asia to Africa and connect to the systems of Europe and Japan.

In the next five years the Indian airspace will get more crowded and the chances of accidents may increase. To reduce the chances of future air disasters, Airports Authority of India (AAI) and Indian Space Research Organisation (ISRO) is implementing a Satellite Based Navigation System (SBNS).

Praful Patel, minister of state for civil aviation says:

The scope for GAGAN extends far beyond Indian borders. It reaches up to Africa and south East Asia. It is a huge airspace that we can monitor with this technology

When ISRO’s satellites are placed into orbit, India will join an elite club that includes USA, Russia and European Union, who run their own GPS networks.

The GAGAN project receives GPS signals from international satellites, but it boosts their accuracy, locking a plane’s position anywhere in India to within three meters. This is made possible by tracking satellites from 15 locations across India and comparing and correcting their data in Bangalore.

Expectations of GAGAN

• Enhanced navigation performance for critical applications like
• Civil Aviation
• Mining
• Marine Navigation
• Train & Road Transport
• Precision Farming
• Search and Rescue (SAR) operations
• Surveying and Mapping (Geodetic & Geodynamic)

GAGAN Orbit Details

The baseline satellite constellation consists of 24 satellites positioned in six earth-centered orbital planes. The orbital period of a GPS satellite is one-half of a sidereal day or 11 hours 58 minutes. The orbits are nearly circular and equally spaced about the equator at a 60-degree separation with an inclination of 55 degrees relative to the equator. The orbital radius is approximately 26,600 km. With the baseline satellite constellation, users with a clear view of the sky have a minimum of four satellites in view.

Draw Backs of Current Augmentation

• Accuracy is not sufficient (even with Selective Availability off, vertical accuracy>10m)
• Current GPS constellation cannot support requirements for all phases of flight
• Availability and continuity must be met
• Integrity is not guaranteed (all satellites are not monitored at all times; time-to-alarm is from minutes to hours, no indication of quality of service)

Uses of GAGAN for Civil Aviation Sector

• Improved Efficiency/Economy
• Direct Routes
• Increased Fuel savings
• Precision approach at all Runways
• Significant cost savings due to withdrawal of ground aids
• Reduced workload of Flight Crew and ATCOs
• Improved Capacity through reduced aircraft separation
• Higher Accuracy, Global Coverage
• Improved Safety
• Controlled Flight into Terrain (CFIT)
• Enhanced Air-to-Air Surveillance: ADS-B
• Availability of MSAW facility (Min. Safe Altitude Warning)
• Reduced Noise Pollution

Uses of GAGAN for Non-Civil Aviation Sector

Marine Navigation

Train & Road transport

Precision Farming

Search and Rescue (SAR) operations

Surveying (Geodetic & Geodynamic)

Scientific community

The system provides enhanced safety features for the airlines as they would be able to have precision approach guidance towards runways in any weather conditions, the officials said. It will also increase air-to-air surveillance.