GPS-aided GEO augmented navigation
The GPS-aided GEO augmented navigation (GAGAN) is an implementation of a regional satellite-based augmentation system (SBAS) by the Government of India.[2] It is a system to improve the accuracy of a GNSS receiver by providing reference signals.[3] The Airports Authority of India (AAI)'s efforts towards implementation of operational SBAS can be viewed as the first step towards introduction of modern communication, navigation and surveillance / air traffic management system over the Indian airspace.[4]
GPS-aided GEO augmented navigation
Regional satellite-based augmentation system
1.5 m or 4 ft 11 in (horizontal),
2.5 m or 8 ft 2 in (vertical)
2001
26,600 km (approx)
15 years
2013–14[1]
The project has established 15 Indian Reference Stations (INRES), 2 Indian Master Control Centre (INMCC) and 3 Indian Land Uplink Station (INLUS) and installation of all associated software and communication links.[5] It will be able to help pilots to navigate in the Indian airspace by an accuracy of 3 m (9.8 ft) and will be helpful for landing aircraft in marginal weather and difficult approaches like Mangalore International and Kushok Bakula Rimpochee airports.[6]
Implementation[edit]
The ₹774 crore (US$93 million) project was deployed in three phases through 2008 by the Airports Authority of India with the help of the Indian Space Research Organisation's (ISRO) technology and space support.[7] The goal is to provide navigation system for all phases of flight over the Indian airspace and in the adjoining area. It is applicable to safety-to-life operations, and meets the performance requirements of international civil aviation regulatory bodies.[8]
The space component became available after the launch of the GAGAN payload on the GSAT-8 communication satellite, which was successfully launched. This payload was also part of the GSAT-4 satellite that was lost when the Geosynchronous Satellite Launch Vehicle (GSLV) failed during launch in April 2010. A final system acceptance test was conducted during June 2012 followed by system certification during July 2013.[7]
All aircraft being registered in India after 1 July 2021 are mandated to be outfitted with GAGAN equipment.[9] The first aircraft to land using GAGAN system was an ATR-72 aircraft of IndiGo. The landing was carried out 29 April 2022 in Kishangarh Airport, Rajasthan.[10]
In 2024, reports suggested that all the new aircraft that were ordered by Air India and IndiGo will be equipped with GAGAN systems whereas many of the turboprop aircraft in India like ATR-72 and De Havilland Canada Dash 8. The GAGAN systems will be primarily operationalised in smaller airports lacking instrument landing system (ILS) whereas larger airports with ILS will keep it as a backup option in case of non availability of such infrastructures.[11]
Technology Integration[edit]
GAGAN is now in operational phase and is compatible with other SBAS systems such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS) and the MTSAT Satellite Augmentation System (MSAS) and will provide seamless air navigation service across regional boundaries.[15] While the ground segment consists of fifteen reference stations and a master control centre, which will have sub systems such as data communication network, SBAS correction and verification system, operations and maintenance system, performance monitoring display and payload simulator, Indian land uplinking stations will have dish antenna assembly. The space segment will consist of one geo-navigation transponder.
A GAGAN-based flight management system will be able to save time and money of operators by controlling climb, descent, and engine performance profiles. The utilization of operator-preferred trajectories will increase, leading to increased efficiency and flexibility from the FMS. It will enhance access to airports and airspace in any weather conditions and enhance compliance with environmental and obstacle clearance requirements. By establishing more exact terminal area procedures with parallel routes and environmentally optimized airspace corridors, it will also improve reliability and decrease delays.[16]
Applications[edit]
Karnataka Forest Department has used GAGAN to build a new, accurate and publicly available satellite based database of its forestlands. This is a followup to the Supreme Court directive to states to update and put up their respective forest maps. The geospatial database of forestlands pilot has used data from the Cartosat-2 satellite. The maps are meant to rid authorities of ambiguities related to forest boundaries and give clarity to forest administrators, revenue officials as also the public, according to R.K. Srivastava, chief conservator of forests (headquarters).[24]
The Indian National Centre for Ocean Information Services (INCOIS) along with AAI has launched a new satellite-based GEMINI (Gagan Enabled Mariner's Instrument for Navigation and Information) system that will alert deep-sea fishermen of upcoming disasters. The GEMINI app on the cellphone decodes the signals from GEMINI device and alerts the user on imminent threats like cyclones, high waves, strong winds along with PFZ and search and rescue mission.
Various Indian manufactured missiles including the BrahMos will use GAGAN for guidance.[25]