13/10/2026
A Bengaluru Aerospace Scientist Built the Made-in-India System That Reads Fog for Pilots
Dr Shubha Venkatesha Iyengar of Bengaluru’s National Aerospace Laboratories led the development of Drishti, India’s indigenous runway visibility system, now deployed at more than 100 aviation locations to help pilots and air traffic controllers navigate low-visibility conditions.
This story is part of “India Invented This?” — The Better India’s weekly trivia series that uncovers the Indian minds, ideas and innovations behind inventions that have shaped the way we live. From ingenious solutions created by scientists and engineers to technologies developed in response to some of India’s biggest challenges, each story goes beyond the invention to explore the problem it solved, the impact it created and why it still matters today.
On a foggy winter morning, a road can disappear from view within minutes. Cars slow down, headlights come on, and even familiar turns suddenly feel uncertain.
Now imagine being 700 feet above the ground, trying to land an aircraft when the runway ahead is hidden behind a thick veil of fog.
So, when the sky turns unclear, how do planes know where to land?
The answer, in part, lies in a piece of Indian technology called Drishti — a homegrown runway visibility measuring system that helps pilots and air traffic controllers know just how much of the runway can actually be seen.
And behind this technology is aerospace scientist Dr Shubha Venkatesha Iyengar, who spent more than four decades at the CSIR-National Aerospace Laboratories (NAL), working on technologies designed to make flying safer in difficult weather.
Giving runways a pair of eyes
Fog, rain, dust and smog can make the final moments of a flight particularly challenging. Pilots need to know the Runway Visual Range (RVR), essentially, how far down the runway they can see.
That is where Drishti comes in.
The system uses a transmitter and receiver placed about 30 metres apart. A beam of light travels between them, and the system measures how much that light is scattered or absorbed by particles in the atmosphere. From this, it calculates visibility and sends real-time information to pilots and air traffic controllers.
In dense fog, visibility can fall below 25 metres. On a clear day, it can stretch beyond 2,000 metres. Drishti is designed to measure across this wide range, giving aviation teams a clearer picture of conditions on the ground.
It may sound like a small task, but in aviation, a few metres of visibility can make a meaningful difference.
An Indian answer to an Indian problem
Before Drishti, Indian airports largely depended on imported transmissometers for runway visibility measurements. These systems were expensive and could be difficult to maintain.
Dr Shubha and her team at NAL set out to build an indigenous alternative that could withstand the weather conditions Indian airports regularly encounter.
