India has achieved an important milestone in civil aviation with the successful use of its indigenous satellite-based navigation system (SBAS), Gagan, to land a commercial passenger aircraft. On Friday, 27th June, an IndiGo Airbus A320 made a routine landing at Udaipur airport, but behind the scenes, it marked a historic first. Instead of depending on the traditional ground-based radio landing system, the aircraft completed its approach using Gagan, making it the first full-sized passenger jet in India to do so.
The Directorate General of Civil Aviation (DGCA) confirmed that while smaller turboprop aircraft had previously tested similar approaches, this was the first successful landing by a commercial narrow-body passenger aircraft using the indigenous technology.
What is Gagan, and why is it important?
Gagan (GPS Aided GEO Augmented Navigation) is a satellite-based navigation augmentation system jointly developed by the Indian Space Research Organisation (ISRO) and the Airports Authority of India (AAI). Its primary purpose is to improve the accuracy and reliability of GPS signals used by aircraft during navigation, especially while landing.
The system broadcasts signals through the GSAT-8 and GSAT-10 communication satellites, which remain in fixed positions over the equator and provide continuous coverage across Indian airspace.
🚨 India has achieved a major aviation milestone with its first-ever satellite-based landing system approach on a jet aircraft.
— Indian Tech & Infra (@IndianTechGuide) June 28, 2026
• An IndiGo Airbus A320 successfully completed a GAGAN-based precision landing in Udaipur.
• This marks the first successful use of GAGAN on an…
Many people confuse Gagan with NavIC, India’s own satellite navigation system, but both serve different purposes. NavIC is an independent navigation network that tells users where they are. Gagan, on the other hand, does not provide location information by itself. Instead, it improves the accuracy of GPS signals that aircraft already receive.
Gagan constantly checks GPS signals, identifies any errors, corrects them and tells pilots whether the navigation data is safe enough to be used for flying and landing.
Why isn’t ordinary GPS enough for aircraft?
The GPS we use every day on our mobile phones works well enough for finding directions on roads, but aircraft require much greater precision. During landing, especially in poor weather or low visibility, even a small positioning error can become a serious safety concern.
One of the biggest reasons for this is the Earth’s ionosphere, a layer of the atmosphere filled with electrically charged particles. GPS signals slow down and bend while passing through this region, creating errors in the aircraft’s calculated position.
This problem is even more significant in India because the country lies under the Equatorial Ionisation Anomaly, an area where atmospheric conditions change frequently and cause larger GPS inaccuracies.
Without correction, ordinary GPS cannot provide the level of accuracy required for precision landings.
How does Gagan correct GPS signals?
Gagan solves this problem through a network of 15 reference stations spread across India. These stations are installed at locations whose exact position is already known with extremely high accuracy.
Each station continuously receives GPS signals and compares the location shown by GPS with its actual position. If there is any difference, the system immediately recognises it as an error.
The correction is then sent to a central processing facility, which calculates the accurate information and forwards it to India’s communication satellites. These satellites broadcast the corrected signals back to aircraft flying in Indian airspace. The aircraft automatically applies these corrections through its onboard receiver, giving pilots a much more accurate picture of their position.
Another major advantage is safety. Gagan constantly monitors the quality of GPS signals. If the corrected signal becomes unreliable for any reason, it immediately alerts the pilots so they can switch to another navigation method.
Historic landing at Udaipur
The IndiGo Airbus A320 used what is known as an LPV (Localiser Performance with Vertical Guidance) approach while landing at Udaipur.
This type of approach provides both horizontal and vertical guidance to pilots, almost matching the accuracy of the traditional Instrument Landing System (ILS) that many major airports use.
The biggest difference is that LPV approaches do not require expensive radio equipment to be installed at every airport. Instead, satellite technology provides the guidance.
That is what made the Udaipur landing historic. A commercial passenger aircraft completed a precision approach using India’s own satellite-based navigation system.
Why is this important for India’s airports?
India is rapidly expanding its aviation network under regional connectivity schemes, with many smaller cities getting airports for the first time.
However, installing a full Instrument Landing System at every airport is extremely expensive and requires regular maintenance. Gagan changes this equation completely.
A senior pilot explained the importance of the technology, saying, “For decades, aircraft have relied on ground-based navigation systems to guide pilots safely to the runway, especially during poor weather or low visibility. While these systems have served aviation well, they are expensive to procure and maintain. SBAS has fundamentally changed the way aircraft navigate and land. Instead of depending solely on equipment installed at airports, it allows pilots to receive precise horizontal and vertical guidance even at airports that do not have conventional precision landing systems.”
This means many regional airports can offer precision-guided landings without spending heavily on new ground infrastructure.
The country is adding airports under the UDAN regional connectivity scheme, but installing a full Instrument Landing System at every airport is expensive and requires continuous maintenance.
Safer flights and fewer disruptions
Satellite-guided approaches will allow aircraft to land more safely during bad weather, reducing cancellations, delays and diversions. Airlines will be able to operate more efficiently, while passengers will experience more reliable flight schedules.
In a document on SLS, aerospace major Airbus says: “This function enables pilots to perform ‘straight-in’ approaches using satellite positioning into airports, even in low-visibility conditions. Facilitating precision approach access to secondary airports, SLS capability enhances the airlines’ operations by enabling stable approaches, especially at airports currently not having precision approach means; at main runways as a backup to ILS (like during maintenance), or at alternate airports in case of diversion.”
An official overseeing this exercise on condition of anonymity said, “Almost half of the recorded controlled flight into terrain accidents occurred during approach and landing without vertical guidance. SLS allows approaches with vertical and lateral guidance to 200 ft above the ground, without expensive ground installation like ILS.”
A major boost for India’s aviation future
ISRO has designed Gagan with two major objectives. The first is to provide the accuracy, reliability, and safety needed for aircraft to execute secure approaches and landings in challenging weather conditions. The second is to improve overall air traffic management by allowing aircraft to fly more efficient routes across Indian airspace.
The Airports Authority of India has already published 23 LPV approach procedures across airports, and this number is expected to cross 40 by the end of the year. As more airports adopt LPV procedures and more airlines equip their aircraft with SBAS-compatible systems, Gagan is expected to become a key pillar of Indian aviation.
ISRO has designed the technology not only to improve landing safety but also to make flight paths more efficient and improve air traffic management across the country. Gagan is also compatible with similar satellite augmentation systems used internationally, allowing aircraft to receive enhanced navigation support even while flying across different regions.
