Policy Update
Tuba Athar
Background
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. Satellite Navigation service is an emerging satellite-based system with commercial and strategic applications.
ISRO is committed to providing satellite-based Navigation services to meet the emerging demands of the Civil Aviation requirements and to meet the user requirements of the positioning, navigation, and timing based on the independent satellite navigation system. The system is a Space-Based Augmentation System (SBAS). To meet the Civil Aviation requirements, ISRO has been working jointly with the Airport Authority of India (AAI) to establish the GPS Aided Geo Augmented Navigation (GAGAN) system, which has an estimated cost of Rs 774 crores. The Project was completed in 8 years.
GAGAN Final System Acceptance Test (FSAT) was completed on 16th-17th July 2012. Further, the GSAT-8 satellite-GAGAN Payload has been integrated with Indian Land Uplink station-1(INLUS), Bangalore, and GAGAN SIS (Signal in Space) is available since Dec 15, 2011. The GSAT-10 satellite has been integrated with the Indian Land Uplink station-2, Bangalore, and the second GAGAN SIS is available from April 2013. The backup Delhi INLUS has also been Operational since March 2013 and is integrated with GSAT-8, and the system has been fully operationalised since May 2015.
National Civil Aviation Policy (NCAP-2016) prescribes that new aircraft being registered in India from 1st January 2019 will mandatorily have to be GAGAN-enabled. DGCA issued a public notice stating that “All aircraft being registered in India from 1st January 2019 will mandatorily have to be GAGAN enabled.” (Subsequently revised to 1st July 2021)
Objectives
The main objectives of GAGAN are:-
- To provide Satellite-based Navigation services with the accuracy and integrity required for civil aviation applications
- To provide better Air Traffic Management over Indian Airspace
The system is interoperable with other international SBAS systems like US-Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), and Japanese MTSAT Satellite Augmentation System (MSAS), etc., and provides seamless navigation across regional boundaries. The GAGAN Signal-In-Space (SIS) is available through GSAT-8 and GSAT-10 satellites. GAGAN’s functional performance and operational requirements are governed by the specifications mentioned in the international standards.
Functioning
GAGAN system has been fully operationalized since May 2015 and can provide Navigation Services to Departure, en-route, and landing operations to suitably equipped aircraft. The System provides accurate and high-integrity satellite signals for precision air navigation over the entire Indian airspace.
The details of the GAGAN system installations are as follows:
- The GAGAN system consists of 15 Indian Reference Stations (INRES). The fifteen INRES are installed at various airports in India at Delhi, Ahmedabad, Bengaluru, Thiruvananthapuram, Kolkata, Guwahati, Portblair, Jammu, Gaya, Jaisalmer, Nagpur, Dibrugarh, Bhubaneswar, Porbandar, and Goa.
- Two Indian Master Control Centers (INMCCs) located in Bengaluru
- Three Indian Lank Uplink Stations (INLUSs), two are located in Bengaluru and one in Delhi
- Four chains of networks (OFC and VSAT)
- Three GEO satellites with GAGAN payloads
Source: https://www.ursc.gov.in/navigation/gagan.jsp
The GAGAN uses a system of ground stations to provide necessary augmentations to the GPS standard positioning service (SPS) navigation signal. A network of precisely surveyed ground reference stations (INdian Reference Stations, INRES) is strategically positioned across the country to collect GPS satellite data. Using this information, the master control centre (INdian Master Control Centre, INMCC) generates messages to correct signal errors. These correction messages are then uplinked through (INdian Land Uplink Station, INLUS) and broadcast through communication satellites (Geostationary) to receivers onboard aircraft using the same frequency as GPS.
Performances and Impact
India is the fourth country in the world, after the USA, Europe, and Japan, to take up the challenge of establishing the regional SBAS that will redefine navigation over India and adjacent regions. 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. It covers the area from Africa to Australia and has expansion capability for seamless navigation services across the region.
It provides accuracy, availability, and integrity essential for each phase of flight, en route to the approach for airports within the GAGAN service volume. This makes airline operations more efficient and effective, increases air safety, and improves fuel efficiency. Further, with vertical guidance at runways, a significant cost is saved due to the withdrawal of ground aids and reduced workload of airline crews and traffic controllers. One essential component of the GAGAN project is the study of the ionospheric behaviour over the Indian region. This makes India the world’s third country with such precision approach capabilities.
Though GAGAN has been developed for aviation, it can provide benefits beyond all modes of transportation, including maritime, highways, railroads, and public services such as defense services, security agencies, telecom industry, and personal users of position location applications.
For example, in Non-Aviation, GAGAN helps in Disaster Management. With the use of GAGAN message service (GMS), early warning messages can be broadcast on the occurrence of natural disasters, calamities, dangers for the safety of life within the GAGAN coverage area for search and rescue messages, relief and mitigation-related messages, meteorological information, and other uses. GAGAN can enhance safety, mobility, regulation, and enable payment applications.
In the road sector, it can offer smart mobility for lane guidance, better traffic management, speed control, traffic violation, and real-time tracking of public transportation assets. With the use of GAGAN, the initiation of alarm and barrier closure can be automated, and train movements and automated train stopping can be monitored to reduce the risk of accidents. GAGAN can improve Navigation and Positioning in the Indian Subcontinent and Inland waterways by tracking the proximity of ships, enabling safe docking of vessels at ports, enhancing coastal security, and tracking of ships.
Issues and Limitations
- Limited Awareness and Adoption Beyond Aviation: Though GAGAN was designed with aviation in mind, its utility in other sectors (agriculture, railways, maritime, etc.) is underutilised.
- Dependency on GPS signals: GAGAN augments GPS (a U.S.-owned system), making it indirectly dependent on foreign infrastructure. It can be subjected to GPS signal degradation or intentional denial during geopolitical tensions.
- Limited Accuracy Compared to Global Standards: GAGAN offers 3–5 meter accuracy, sufficient for many aviation purposes but inferior to some other SBAS like WAAS (USA) or EGNOS (Europe), and to RTK/PPP solutions used in high-precision applications.
- Coverage Constraints: The coverage is optimized for the Indian subcontinent, but performance degrades outside its primary footprint.
- Lack of Interoperability with NavIC: GAGAN and NavIC (India’s regional navigation satellite system) are not fully integrated. India has yet to offer an indigenous high-accuracy, dual-frequency solution combining GAGAN and NavIC.
- Slow Ground Infrastructure Expansion: Limited number of reference stations and ground uplink infrastructure as compared to more mature systems like WAAS, which affects the integrity and robustness of signal corrections in remote areas.
Way forward
While India has leapt ahead in providing navigation and positioning services however it needs more to compete with the global space-based augmentation system of the USA, Europe, and Japan. Some of the suggestions could be integrating GAGAN with NavIC and developing a seamless Indian positioning system. Expanding application in other sectors, along with upgrading ground infrastructure, ensuring consistent signal integrity across all of India, and integrating GAGAN into geospatial education and skill development programs for creating awareness and incentivizing use. Moreover, it enhances international cooperation with neighboring SBAS, such as Japan’s MSAS and Russia’s SDCM.
References
- Press Information Bureau. (2015, August 10). GAGAN System. https://www.pib.gov.in/newsite/PrintRelease.aspx?relid=124704
- Press Information Bureau. (2022, December 08). Consultative committee of Ministry of Civil Aviation meets in New Delhi to discuss GAGAN (GPS Aided Geo Augmented Navigation). https://www.pib.gov.in/PressReleasePage.aspx?PRID=1881866
- Press Information Bureau. (2015, July 13). Civil Aviation Minister Launches GAGAN System. https://www.pib.gov.in/newsite/PrintRelease.aspx?relid=123209#:~:text=Civil%20Aviation%20Minister%20Launches%20GAGAN,Aviation%20Minister%20Launches%20GAGAN%20System
- https://www.isro.gov.in/satellitenavign.html, retrieved on July 16, 2025.
- https://www.aai.aero/en/content/what-gagan, retrieved on July 16, 2025.
- https://www.ursc.gov.in/navigation/gagan.jsp, retrieved on July 16, 2025.
- https://economictimes.indiatimes.com/definition/gagan?from=mdr, retrieved on July 16, 2025.
About the contributor: Tuba Athar is a research intern at IMPRI. She is pursuing a PhD from the Centre for the Study of Regional Development, Jawaharlal Nehru University, New Delhi.
Acknowledgement: The author sincerely thanks Aasthaba Jadeja and other IMPRI fellows for their valuable contribution.
Disclaimer: All views expressed in the article belong solely to the author and not necessarily to the organisation.
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