The demonstration flight was conducted on June 27 using a Satellite-Based Landing System (SLS) approach instead of the conventional Instrument Landing System (ILS). Although IndiGo had previously demonstrated the technology on its ATR turboprop aircraft, this was the first successful application on a commercial Airbus A320 jet. Passengers onboard experienced no noticeable difference during the landing, as the aircraft was guided entirely by satellite signals rather than the ground-based radio beams traditionally used at major airports.
The achievement represents a major advancement in aviation technology by showcasing an effective alternative to the Instrument Landing System, which serves as the primary precision landing aid at many airports. Since ILS infrastructure requires substantial installation and maintenance costs, several smaller and secondary airports do not have the facility. Satellite-guided precision approaches are expected to significantly enhance operational safety at such airports while expanding access to precision landing capabilities.
During the demonstration, the Airbus A320 executed a Localiser Performance with Vertical Guidance (LPV) approach. The procedure provides pilots with both lateral and vertical guidance to the runway, delivering precision comparable to an Instrument Landing System approach without requiring specialized ground equipment at the airport. According to Airbus, the technology enables stable, straight-in approaches using satellite positioning, including during low-visibility conditions. It also provides an effective backup whenever an Instrument Landing System is unavailable due to maintenance or when aircraft are diverted to alternate airports.
GAGAN, which stands for GPS Aided GEO Augmented Navigation, is India's Satellite-Based Augmentation System jointly developed by the Indian Space Research Organisation (ISRO) and the Airports Authority of India (AAI). Unlike the Global Positioning System (GPS) or India's regional navigation constellation NavIC, GAGAN does not independently determine an aircraft's position. Instead, it continuously enhances GPS signals by correcting navigation errors and monitoring their reliability before transmitting accurate information to aircraft.
The correction signals are transmitted through ISRO's geostationary communication satellites GSAT-8 and GSAT-10, positioned above the equator to provide uninterrupted coverage across Indian airspace. While NavIC functions as an independent regional navigation system capable of determining location on its own, GAGAN operates solely as an augmentation system designed to improve the accuracy and reliability of GPS for aviation operations.
Standard GPS technology, commonly used in smartphones, generally provides positioning accuracy within a few metres, which is sufficient for everyday navigation but inadequate for guiding commercial aircraft safely during precision landings. As GPS signals travel through the ionosphere, atmospheric disturbances delay and distort them. These challenges are particularly significant over India because the country lies beneath the equatorial ionisation anomaly, a region where upper atmospheric disturbances can rapidly alter navigation accuracy. Commercial aircraft therefore require not only highly precise positioning but also continuous assurance that navigation information remains reliable throughout the approach.
GAGAN addresses these challenges through a network of 15 precisely surveyed ground reference stations located across India. Each station continuously compares its known geographical position with GPS-derived data to detect even the smallest navigation errors. The corrections are processed at dedicated control centres before being transmitted through GSAT-8 and GSAT-10. The satellites then broadcast the corrected navigation information back to aircraft in real time, substantially improving positioning accuracy.
An equally important feature of GAGAN is navigation integrity, which enables the system to continuously monitor signal quality and immediately alert pilots within seconds if navigation information becomes unreliable. This allows flight crews to take prompt corrective action whenever necessary, further enhancing aviation safety.
IndiGo first introduced Localiser Performance with Vertical Guidance operations on its ATR turboprop fleet in 2022 and has now expanded Satellite-Based Augmentation System-enabled operations across its fleet, paving the way for wider adoption of satellite-guided precision approaches throughout India.
The Airports Authority of India has already published 23 Localiser Performance with Vertical Guidance approach procedures at airports across the country, with the total expected to exceed 40 before the end of this year. As additional airports adopt these procedures and more airlines equip their aircraft with Satellite-Based Augmentation System capability, GAGAN is expected to become a key component of India's future aviation infrastructure by improving operational safety, efficiency, and accessibility.
According to ISRO, GAGAN has two primary objectives. The first is to provide the accuracy and navigation integrity required for precision civil aviation operations. The second is to improve air traffic management by enabling aircraft to operate along more direct and efficient flight routes. The system has also been designed to function seamlessly with similar satellite augmentation systems used internationally, allowing aircraft to maintain continuous navigation guidance while operating across international airspace.
The successful satellite-guided landing of an IndiGo Airbus A320 represents a historic milestone for Indian aviation. It demonstrates the growing capability of India's indigenous navigation technology and strengthens the country's efforts to expand precision landing infrastructure, improve flight safety, and support the continued growth of its rapidly expanding aviation network.
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