Gagan guides jets, NavIC guards India. Here's why the country needs both
India has two satellite navigation systems, Gagan and NavIC, and most people cannot tell them apart. Here is what each does, why they are not rivals, and why losing either would hurt the country.
In the skies over Rajasthan on June 27, 2026, an IndiGo Airbus A320 lined up for Udaipur and let satellites bring it down. Most runways guide a jet in with a radio beam fired from the ground. Udaipur did not need to.
The aircraft already knew exactly where it was, because a system called Gagan was watching from orbit and correcting its position in real time.
While the Indian Space Research Organisation aced the Gagan integration, its other space navigation system is in trouble. NavIC, the country's homegrown answer to GPS, has quietly slipped below the minimum strength it needs to work at all.
Two Indian navigation systems. One is landing jets, the other fighting to stay alive. But India needs both functioning at their optimal capacity.
We look at why India built two satellite navigation systems instead of one, and why losing either would hurt.
WHAT IS THE DIFFERENCE BETWEEN GAGAN AND NAVIC?
Start with the thing everyone gets wrong. They are not rivals. They sit at opposite ends of the navigation grid.
NavIC is a positioning system. Like the American GPS, it tells you where you are, all by itself, using its own satellites.
Gagan does not do this. Gagan is not an individual positioning satellite. It is a corrector, a system that takes the GPS signal everyone already uses and scrubs the errors out of it.
Think of GPS as a slightly unreliable narrator. NavIC is India writing its own narrator from scratch. Gagan is India hiring a fact-checker to follow the American narrator around and fix its mistakes in real time. Different jobs entirely.
WHAT DOES GAGAN DO, AND WHY DOES IT MATTER FOR FLIGHTS?
Gagan stands for GPS Aided GEO Augmented Navigation. It was built jointly by the Indian Space Research Organisation (Isro) and the Airports Authority of India (AAI), and its single purpose is aviation.
The plain GPS in your phone is accurate to a few metres, fine for finding a street, useless you are landing a 70-tonne jet through clouds. As GPS signals pass through the ionosphere, the electrically charged upper layer of the atmosphere, they get bent and slowed, throwing the reading off. Gagan fixes this.
A network of ground stations across India, each sitting at a spot surveyed to the centimetre, listens to GPS and works out exactly how wrong it is at that moment. That correction is beamed up to two satellites, GSAT-8 and GSAT-10, parked high above the equator, which broadcast the fix down to aircraft.
Crucially, Gagan also tells the pilot how much to trust the signal and shouts a warning within seconds if it cannot be trusted. That property, called integrity, is what lets aircraft use it to land.
WHAT IS NAVIC, AND WHY IS IT IN TROUBLE?
NavIC, short for Navigation with Indian Constellation, is the bigger ambition.
It is India's own positioning system, designed as a constellation of seven satellites covering the country and 1,500 km beyond its borders, fixing locations to within about 20 metres for civilian users, with a separate encrypted signal reserved for the military.
The problem is keeping it alive. Satellite navigation depends on timing measured at billionths of a second, which is why every navigation satellite carries an atomic clock, an exquisitely precise timekeeper that counts the steady vibrations of atoms. A tiny timing error becomes a position error of hundreds of metres.
Navigation needs at least four satellites working together to fix a position, and after one satellite's last atomic clock failed on March 13, 2026, the system India built for independence is, for now, running on fumes.
WHY CAN GAGAN NOT JUST REPLACE NAVIC?
Here is the trap. If Gagan works so well that it landed a jet, why bother nursing NavIC back to health at all?
Because Gagan is only as alive as GPS. It does not navigate independently. Strip away the American signal it corrects, and Gagan has nothing to correct. It is a brilliant fact-checker chained to someone else's narrator. And that signal can be taken away.
A navigation signal controlled by another country can be jammed, where an attacker floods the area with radio noise until receivers hear only static, or spoofed, where a convincing fake tricks a receiver into believing it is somewhere it is not, or simply switched off over a region by the country that owns it.
India has long understood the risk of depending on a system it does not control. That dependence is precisely the gap NavIC exists to close.
SO WHY DOES INDIA NEED BOTH?
Because they cover two completely different weaknesses.
Gagan answers the question of precision for safety. It makes a borrowed signal sharp and trustworthy enough to guide aircraft onto runways, which is invaluable at the many regional airports that cannot afford expensive ground landing equipment. It is also built to work alongside similar systems abroad, so flights cross borders without losing guidance.
NavIC answers the question of sovereignty. It guarantees that, whatever happens to GPS, India keeps a positioning and timing signal of its own, feeding railways, fishing boats, disaster alerts and the armed forces. Some 8,700 trains already rely on it.
One makes the world's signal better. The other makes sure India is never left without one. The Udaipur landing showed the first quietly doing its job. NavIC's struggle this year is the sharpest possible reminder of why the second can never be allowed to fail.
#TheDailyWhy
In the skies over Rajasthan on June 27, 2026, an IndiGo Airbus A320 lined up for Udaipur and let satellites bring it down. Most runways guide a jet in with a radio beam fired from the ground. Udaipur did not need to.
The aircraft already knew exactly where it was, because a system called Gagan was watching from orbit and correcting its position in real time.
While the Indian Space Research Organisation aced the Gagan integration, its other space navigation system is in trouble. NavIC, the country's homegrown answer to GPS, has quietly slipped below the minimum strength it needs to work at all.
Two Indian navigation systems. One is landing jets, the other fighting to stay alive. But India needs both functioning at their optimal capacity.
We look at why India built two satellite navigation systems instead of one, and why losing either would hurt.
WHAT IS THE DIFFERENCE BETWEEN GAGAN AND NAVIC?
Start with the thing everyone gets wrong. They are not rivals. They sit at opposite ends of the navigation grid.
NavIC is a positioning system. Like the American GPS, it tells you where you are, all by itself, using its own satellites.
Gagan does not do this. Gagan is not an individual positioning satellite. It is a corrector, a system that takes the GPS signal everyone already uses and scrubs the errors out of it.
Think of GPS as a slightly unreliable narrator. NavIC is India writing its own narrator from scratch. Gagan is India hiring a fact-checker to follow the American narrator around and fix its mistakes in real time. Different jobs entirely.
WHAT DOES GAGAN DO, AND WHY DOES IT MATTER FOR FLIGHTS?
Gagan stands for GPS Aided GEO Augmented Navigation. It was built jointly by the Indian Space Research Organisation (Isro) and the Airports Authority of India (AAI), and its single purpose is aviation.
The plain GPS in your phone is accurate to a few metres, fine for finding a street, useless you are landing a 70-tonne jet through clouds. As GPS signals pass through the ionosphere, the electrically charged upper layer of the atmosphere, they get bent and slowed, throwing the reading off. Gagan fixes this.
A network of ground stations across India, each sitting at a spot surveyed to the centimetre, listens to GPS and works out exactly how wrong it is at that moment. That correction is beamed up to two satellites, GSAT-8 and GSAT-10, parked high above the equator, which broadcast the fix down to aircraft.
Crucially, Gagan also tells the pilot how much to trust the signal and shouts a warning within seconds if it cannot be trusted. That property, called integrity, is what lets aircraft use it to land.
WHAT IS NAVIC, AND WHY IS IT IN TROUBLE?
NavIC, short for Navigation with Indian Constellation, is the bigger ambition.
It is India's own positioning system, designed as a constellation of seven satellites covering the country and 1,500 km beyond its borders, fixing locations to within about 20 metres for civilian users, with a separate encrypted signal reserved for the military.
The problem is keeping it alive. Satellite navigation depends on timing measured at billionths of a second, which is why every navigation satellite carries an atomic clock, an exquisitely precise timekeeper that counts the steady vibrations of atoms. A tiny timing error becomes a position error of hundreds of metres.
Navigation needs at least four satellites working together to fix a position, and after one satellite's last atomic clock failed on March 13, 2026, the system India built for independence is, for now, running on fumes.
WHY CAN GAGAN NOT JUST REPLACE NAVIC?
Here is the trap. If Gagan works so well that it landed a jet, why bother nursing NavIC back to health at all?
Because Gagan is only as alive as GPS. It does not navigate independently. Strip away the American signal it corrects, and Gagan has nothing to correct. It is a brilliant fact-checker chained to someone else's narrator. And that signal can be taken away.
A navigation signal controlled by another country can be jammed, where an attacker floods the area with radio noise until receivers hear only static, or spoofed, where a convincing fake tricks a receiver into believing it is somewhere it is not, or simply switched off over a region by the country that owns it.
India has long understood the risk of depending on a system it does not control. That dependence is precisely the gap NavIC exists to close.
SO WHY DOES INDIA NEED BOTH?
Because they cover two completely different weaknesses.
Gagan answers the question of precision for safety. It makes a borrowed signal sharp and trustworthy enough to guide aircraft onto runways, which is invaluable at the many regional airports that cannot afford expensive ground landing equipment. It is also built to work alongside similar systems abroad, so flights cross borders without losing guidance.
NavIC answers the question of sovereignty. It guarantees that, whatever happens to GPS, India keeps a positioning and timing signal of its own, feeding railways, fishing boats, disaster alerts and the armed forces. Some 8,700 trains already rely on it.
One makes the world's signal better. The other makes sure India is never left without one. The Udaipur landing showed the first quietly doing its job. NavIC's struggle this year is the sharpest possible reminder of why the second can never be allowed to fail.
#TheDailyWhy
