- IndiGo's Airbus A320 completed India's first satellite-guided landing using GAGAN system
- The flight used Satellite-Based Landing System instead of conventional Instrument Landing System
- GAGAN enhances GPS signals for accurate, reliable navigation across Indian airspace
In a first for Indian aviation, an IndiGo Airbus A320 has completed a satellite-guided landing using the country's indigenous GAGAN navigation system during a demonstration overseen by aviation regulator, the Directorate General of Civil Aviation or DGCA.
The flight, conducted on June 27, used a Satellite-Based Landing System (SLS) approach instead of the conventional Instrument Landing System (ILS). While IndiGo's ATR turboprop aircraft had previously demonstrated the technology, this was the first time it was used for a commercial jet. Passengers onboard would have noticed little difference, but the aircraft was guided by satellite signals rather than the ground-based radio beams used at most major airports.
The milestone is significant because it showcases an alternative to the Instrument Landing System (ILS), the precision landing aid installed at many major airports but absent at several smaller and secondary airports due to its high installation and maintenance costs. By enabling precision approaches through satellite guidance, the technology is expected to improve operational safety, especially at airports without ILS infrastructure.
The Airbus A320 carried out what is known as a Localiser Performance with Vertical Guidance (LPV) approach. The procedure provides pilots with both lateral (left-right) and vertical (up-down) guidance to the runway, offering precision similar to an ILS approach without requiring specialised equipment to be installed at the airport itself.
According to Airbus, the capability enables pilots to perform stable, straight-in approaches using satellite positioning, including in low-visibility conditions. Besides enhancing operations at airports without precision landing systems, it can also serve as a backup when ILS is unavailable due to maintenance or support aircraft diverted to alternate airports.
What Is GAGAN?
GAGAN is short for GPS Aided GEO Augmented Navigation, India's Satellite-Based Augmentation System (SBAS), jointly developed by the Indian Space Research Organisation (ISRO) and the Airports Authority of India (AAI).
Unlike GPS or India's own NavIC navigation constellation, GAGAN does not independently determine an aircraft's position. Instead, it enhances existing GPS signals by correcting their errors and continuously monitoring their reliability before the information reaches pilots.
The correction signals are transmitted through ISRO's geostationary communication satellites GSAT-8 and GSAT-10, positioned over the equator to provide continuous coverage across Indian airspace.
The distinction between GAGAN and NavIC is important. While NavIC is an independent regional navigation system that determines location on its own, much like GPS, GAGAN functions solely as an augmentation system, making GPS more accurate and dependable for aviation operations.
Why GPS Alone Cannot Guide A Jet
The GPS used in smartphones is generally accurate to within a few metres, which is sufficient for everyday navigation but far from precise enough to guide a commercial aircraft safely to a runway.
As GPS signals travel through the ionosphere, they are delayed and distorted by atmospheric conditions. These errors are especially pronounced over India because the country lies beneath the equatorial ionisation anomaly, a region where disturbances in the upper atmosphere can cause navigation errors to fluctuate rapidly.
For precision landings, aircraft require not only highly accurate positioning but also continuous assurance that the navigation data can be trusted.
How GAGAN Improves Accuracy
GAGAN overcomes these limitations through a network of 15 precisely surveyed ground reference stations spread across India. Each station continuously compares its known position with the location reported by GPS, allowing the system to detect even the smallest errors.
These corrections are processed at dedicated control centres before being transmitted to GSAT-8 and GSAT-10. The satellites then broadcast the corrected navigation data back to aircraft in real time, significantly improving positional accuracy.
Equally important is what aviation refers to as "integrity"- the system's ability to continuously monitor navigation signals and alert pilots within seconds if the information becomes unreliable, allowing them to take immediate corrective action.
A Wider Aviation Push
IndiGo first introduced LPV 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 approaches.
AAI has already published 23 LPV approach procedures across airports in India, and that number is expected to exceed 40 by the end of this year.
As more airports introduce LPV procedures and more airlines equip their aircraft with SBAS capability, GAGAN is expected to play a central role in the future of Indian aviation by making air travel safer, more efficient, and more accessible.
According to ISRO, the system has two primary objectives: providing the accuracy and integrity required for precision civil aviation operations and improving air traffic management by enabling aircraft to fly more direct and efficient routes. GAGAN has also been designed to operate seamlessly with similar satellite augmentation systems used internationally, allowing aircraft to maintain continuous navigation guidance while flying across national borders.
This first satellite-guided landing by a commercial jet marks a significant step towards achieving those goals and expanding precision navigation capabilities across India's rapidly growing aviation network.
