IndiGo A320 Makes History with India's First Satellite-Based Jet Landing via GAGAN

IndiGo’s commercial passenger jet successfully landed using an indigenous satellite-based navigation system for the first time. IndiGo’s Airbus A320 executed a precision landing at Udaipur Airport by using the GPS-Aided GEO Augmented Navigation (GAGAN) system which is based on indigenous technology, marking a historical milestone in the Indian civil aviation sector.

The navigation system GAGAN is jointly developed by the Indian Space Research Organisation(ISRO) and the Airports Authority of India (AAI). It is a regional turboprop aircraft that has been utilised previously under the Directorate General of Civil Aviation(DGCA) on a trial basis. This was the first time it was used as a full-sized commercial narrow-body jet and achieved success in India. 

The first-ever commercial jet landing by IndiGo was executed as a Localiser Performance with Vertical Guidance approach (LPV), known as a satellite-based landing system(SLS) approach. 

According to data from aerospace major Airbus, nearly half of all controlled flight into terrain (CFIT) accidents happen during approach and landing sequences which lack vertical guidance. GAGAN addresses this vulnerability directly by allowing precise horizontal and vertical guidance down to 200 feet above the ground without needing a multi-million dollar ground installation.

How Does It Work? 

The GAGAN is a Satellite-Based Augmentation System (SBAS) unlike the conventional GAGAN system which relies on positioning networks like GPS or India's own NavIC. GAGAN acts as a hyper-accurate proofreader for existing GPS signals. Instead of calculating coordinates from scratch. 

GAGAN addresses the issue caused by the conventional navigation system, such as the equatorial ionisation anomaly due to which signals frequently bend and slow down and cause positional errors of several meters.  GAGAN neutralizes this problem using a coordinated loop such as 

• Ground reference stations. a network of 15  ground stations, mapped down to the centimeter, is spread across the country. They continuously receive GPS signals with the absolute, unmoving coordinates. 

• It is based on the Central Processing so that discrepancies (errors) are calculated on a real-time basis. 

• To correct the data, it uses the satellite broadcast. It is beamed up to Indian Geostationary Satellites like GSAT-8 and GSAT-10 parked high above the equator. 

• The satellites broadcast the corrected coordinates back down to the cockpit avionics for aircraft integration to provide pilots sub-meter accuracy and an instant warning if the signal integrity drops. 

Conventional Landing Aids vs GAGAN Satellite-Based Landing 

The LPV approach provided pilots with accurate lateral and vertical guidance directly from space with precise guidance down the runway to a 70-tonne jet. It is different from the conventional landing that requires expensive ground-based radio beams from an Instrument Landing System (ILS). Here are the key difference between the ILS and SLS 

What is the Difference between GAGAN and NaVIC?

The Navigation with Indian Constellation (NavIC) and GAGAN are both based on two different systems. GAGAN is a safety and precision booster that enhances a borrowed signal like GPS to make it safe for commercial aviation. 

NavIC is India’s independent sovereign constellation of satellites designed to replace GPS to provide autonomy for critical domestic, military, and civil infrastructure. 

The IndiGo successful commercial landing demonstrates a crucial step in the DGCA’sregulatory approval process to clear GAGAN-enabled approaches for regular commercial jet operations.

Airport Authority of India has published LPV  procedures for 23 airports across India with plans to exceed 40 by the end of the year. The implementation of the SBAS capabilities in commercial airlines, where GAGAN will play an important role which will make regional air travel safer by reducing weather-related disruptions and driving down operation costs for airlines across Indian airspace