GAGAN / GPS-aided GEO Augmented Navigation

GPS Aided Geo Augmented Navigation (GAGAN) To Transform Indian Aviation

Satellite Navigation Programme

Satellite Navigation service is an emerging satellite based system with commercial and strategic applications. ISRO is committed to provide the 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. To meet the Civil Aviation requirements, ISRO is working jointly with Airport Authority of India (AAI) in establishing the GPS Aided Geo Augmented Navigation (GAGAN) system. To meet the user requirements of the positioning, navigation and timing services based on the indigenous system, ISRO is establishing a regional satellite navigation system called Indian Regional Navigation Satellite System (IRNSS).

GAGAN – GPS Aided GEO Augumented Navigation

The Indian Space Research Organization (ISRO) and the Airports Authority of India (AAI) have implemented the GAGAN project as a Satellite Based Augmentation System for the Indian Airspace. The primary objective of GAGAN is to establish a certifiable satellite based augmentation system for safety-of-life applications. The functional performance and operational requirements of GAGAN shall be governed by the specifications as mentioned in the international standards. The system shall have inter-operability with other international SBAS systems like US-WAAS, European EGNOS, and Japanese MSAS etc.

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. GSAT-10 satellite has been integrated with Indian Land Uplink station-2, Bangalore and second GAGAN SIS is available from April 2013. The backup Delhi INLUS has also been Operational since March 2013 and is integrated to GSAT-8.

GAGAN Stability tests were successfully completed in June 2013. The overall performance of the systems was reviewed by the review committee. As part of certification activity, DGCA personnel visited GAGAN complex, Kundalahalli in Bengaluru and carried out final inspection activities on Indian Land Uplink Station (INLUS), Indian Master Control Centre (INMCC), Indian Reference Earth Station (INRES) and other facilities.

The Key elements of GAGAN are:

  • 15 Indian Reference Stations (INRESs)
  • 2 Indian Master Control Centers (INMCCs)
  • 3 Indian Lank Uplink Stations (INLUSs)
  • 4 chains of networks (OFC and VSAT)
  • 3 GEO satellites with GAGAN payloads


GSAT-8 is an Indian geostationary satellites, which was successfully launched using Ariane 5 on 21 May 2011 and is positioned in geosynchronous orbit at 55 degrees E longitude.

GSAT-10 is envisaged to augment the growing need of Ku and C-band transponders and carries 12 Ku Band, 12 C Band and 12 Extended C Band transponders and a GAGAN payload. The spacecraft employs the standard I-3K structure with power handling capability of around 6 kW with a lift off mass of 3400 kg. GSAT-10 was successfully launched by Ariane 5 on 29 September 2012.

GSAT-15 carries 24 Ku band transponders with India coverage beam and a GAGAN payload. was successfully launched on 10 November 2015, 21:34:07 UTC, completing the constellation.

The implementation of GAGAN has numerous benefits to the aviation sector in terms of fuel saving, saving in equipment cost, flight safety, increased air space capacity, efficiency, enhancement of reliability, reduction in work load for operators, coverage of oceanic area for air traffic control, high position accuracy, etc. The quantum of benefits in the aviation sector would depend on the level of utilisation of such benefits.

The successful completion of system stability test during June-July 2013 paved the way for certification of GAGAN System to meet the civil aviation requirements. The objective of Stability Test was to evaluate the system performance and its critical parameters in the integrated live environment using the satellite signals and ground based systems on integrity, accuracy, continuity and availability for aviation use.

India is the fourth country in the world, after USA, Europe and JAPAN, to take up the challenge of establishing the regional SBAS that will redefine the navigation over India and adjacent regions. The footprint of GAGAN will cover huge area beyond Indian Territory, from Africa to Australia and can support seamless navigation across the Globe.

Further, GAGAN is the first system in the world that would be certified to serve the equatorial anomaly region with its unique IONO algorithm designed and developed by ISAC in collaboration with vendor.

The GAGAN is designed to provide the additional accuracy, availability, and integrity necessary to enable users to rely on GPS for all phases of flight, from en route through approach for all qualified airports within the GAGAN service volume.

GAGAN will also provide the capability for increased accuracy in position reporting, allowing for more uniform and high-quality Air Traffic Management (ATM). In addition, GAGAN will provide benefits beyond aviation to 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.

The GAGAN, a safety of life system, has been certified by DGCA to provide NPA (Non Precision Approach) services of RNP-0.1 over Indian FIR (Flight Information Region) and certified for PA service of APV-1.0/1.5 over Indian landmass.

Some of the benefits GAGAN is expected to bring for Civil Aviation sector are:

  • Safety benefits – Vertical guidance improves safety, especially in adverse weather conditions
  • Reduction of circling approaches
  • Environmental benefits–Approach with Vertical Guidance procedures will help facilitate better energy and descent profile management during the final approach
  • Global seamless navigation for all phases of flight including arrival, departure, oceanic and en route
  • Allow direct routings, multiple approaches resulting in considerable fuel savings to airlines and provide for capacity enhancement of airports and airspace

In addition to aviation sector, GAGAN is expected to bring benefits to other sectors like:

  • Navigation and Safety Enhancement in Railways, Roadways, Ships, Spacecraft
  • Geographic Data Collection
  • Scientific Research for Atmospheric Studies
  • Geodynamics
  • Natural Resource and Land Management
  • Location based services, Mobile, Tourism, etc

An IndiGo-operated aircraft landed at Kishangarh airport using an approach process guided by India’s own satellite-based augmentation system named GAGAN, or GPS-aided GEO Augmented Navigation.


  • India is the first country in the Asia Pacific Region to achieve this.
  • Deadline: The Directorate General of Civil Aviation (DGCA) had set a deadline of July 1, 2021 for all India-registered aircraft to be equipped with GAGAN-compliant instruments.
  • Most of India’s fleet is now compliant with GAGAN standards.
  • The only exception is the Boeing 787 aircraft.
  • India joined a small group comprising the US, Japan and Europe with its own satellite-based augmentation system (SBAS).
    • While the SBAS developed by the US, Japan, Europe and India are already operational, there are several more under development.
  • These include:
    • China’s BeiDou SBAS
    • South Korea’s Korea Augmentation Satellite System (KASS)
    • Russia’s System for Differential Corrections and Monitoring (SDCM)
    • Southern Positioning Augmentation Network (SPAN) of Australia and New Zealand.
  • It is a part of the approval process with aviation safety regulator DGCA, which includes training of pilots, validation of approach and simulator sessions.
    • The procedure will be available for usage of commercial flights.

Satellite-based augmentation system (SBAS)

  • The SBAS is a navigation system, which builds on the Global Navigation Satellite Systems (GLONASS), and adds to the accuracy and integrity of these navigation tools.
  • For aircraft operators, both civilian and military, it means that pilots can land aircraft at smaller airports and airstrips using navigation guidance without expensive instrument-based landing systems being installed on the ground.

What is GAGAN?

  • Developed by: GAGAN is an Indian Space-based Augmented Navigation System, jointly developed by AAI and ISRO.
  • It is used to provide lateral and vertical guidance as an aircraft approaches the runway for landing. Its precision is especially useful at small airports.
  • It is the first such system developed for India and neighbouring countries in the equatorial region.
  • Main objectives of GAGAN are to provide Satellite-based Navigation services with accuracy and integrity required for civil aviation applications and to provide better Air Traffic Management over Indian Airspace.
  • It aids during natural disasters like floods and earthquakes by sending messages to affected people.
  • GAGAN uses a system of ground stations in Delhi, Guwahati, Kolkata, Ahmedabad, Thiruvananthapuram, Bengaluru, Jammu and Port Blair to provide necessary augmentation to the GPS navigation signal.
  • A network of precisely surveyed ground reference stations is strategically positioned across the country to collect GPS satellite data.
  • The system will be interoperable with other international SBAS systems and provide seamless navigation across regional boundaries.
  • The GAGAN Signal-In-Space (SIS) is available through GSAT-8 and GSAT-10.

Significance of GAGAN

  • Smaller airports will benefit: Once fully rolled out, it will make several smaller airports such as those in the North-East capable of having compliant aircraft land in low-visibility scenarios.
  • Poor weather and low visibility: This new technology provides a substantial operational benefit in poor weather and low visibility conditions.
  • Safety: Aircraft can derive maximum benefit in terms of improved safety during landing, reduction in fuel consumption, reduction in delays, diversions and cancellations etc
  • Tool to alert before natural disaster: AAI in coordination with Indian National Centre for Ocean Information Services (INCOIS) has implemented GAGAN Message Service (GMS) through which alert messages to fishermen, farmers, and disaster affected people will be sent on the occurrence of natural disasters, calamities, such as flood, earthquake etc.
  • Non-aviation field: The additional capabilities of GAGAN are also being explored to utilise it in non-aviation fields such as railways, surveying, agriculture, power sector, mining etc.
  • Other benefits: While GAGAN is primarily meant for aviation, it will provide benefits to several other segments such as intelligent transportation, maritime, highways, railways, security agencies, telecom, etc.

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