The Full Form of GAGAN is‍ GPS-aided GEO augmented navigation.

The GPS-aided GEO augmented navigation is an implementation of a regional satellite-based augmentation system by the Government of India. It is a system to improve the accuracy of a GNSS receiver by providing reference signals.

GPS Aided GEO Augmented Navigation (GAGAN) is a step by the Indian Government towards initial Satellite-based Navigation Services in India. It is a system to improve the accuracy of a global navigation satellite system (GNSS) receiver by providing reference signals.

The Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) have collaborated to develop the GPS Aided Geo Augmented Navigation (GAGAN) as a regional Satellite Based Augmentation System (SBAS). The GAGAN’s goal is to provide a navigation system to assist aircraft in accurate landing over the Indian airspace and in the adjoining area and applicable to safety-to-life civil operations. GAGAN is inter-operable with other international SBAS systems.

GAGAN Payload is now operational. The satellites GSAT-8 and GSAT-10 satellites have the GAGAN payloads. The third payload of the system will be launched with GSAT-15 satellite which is scheduled for launch in late of 2015.

The total approximate cost of the project is Rs 7.74 billion ($117 million) and is being created in three phases since 2008.

GAGAN is the first Satellite-Based Augmentation System in the world which has been certified for approach with vertical guidance operating in the equatorial ionospheric region.

GAGAN covers the area from Africa to Australia and has expansion capability for seamless navigation services across the region. GAGAN provides accuracy, availability, and integrity essential for each phase of flight, en route the approach for airports within the GAGAN service volume. This makes airline operations more efficient and effective, increase air safety, and fuel efficiency. Further, with vertical guidance at runways, a significant cost will be saved due to withdrawal of ground aids and reduced workload of airline crew and traffic controllers.

One essential component of the GAGAN project is the study of the ionospheric behaviour over the Indian region. GAGAN ionospheric algorithm was developed by ISRO. This makes India the third country in the world which has such precisionapproach capabilities.

GAGAN has been developed for aviation but it will provide benefits to other sectors as well like transportation, railways, surveying, maritime, highways, telecom industry, and security agencies.