NEW DELHI: India’s regional navigation system NaVIC (Navigation with Indian Constellation system), costing upwards of over Rs 3,200 crore, is now hanging by a thread as the number of fully functional navigation satellites in space has dropped to three satellites. NavIC is designed to run effectively with a constellation of seven satellites, though a minimum of four satellites is required for accurate 3D position, navigation, and timing (PNT) services.With Isro failing to launch two navigation satellites (IRNSS-1H in 2017 and NVS-02 in 2025) in recent years due to different reasons like rocket failure, India’s regional system is facing a failure as the satellite numbers have dipped to three — IRNSS-1B, IRNSS-1L, and second-generation NVS-01 — below the minimum requirement of 4 satellites. A major setback occurred after the last atomic clock, which is the heart of a navigation satellite, on board navigation satellite IRNSS-1F stopped functioning on March 10, leaving only three satellites of India’s NaVIC constellation in function.Speaking at the DefSpace symposium here, former IAF chief ACM Rakesh Kumar Singh Bhadauria (Retd) said on Thursday, “NaVIC will be remembered more because of its failure and promises that were not delivered rather than anything. It is high time that NaVIC-type capabilities are redrawn completely”.Former Air Vice Marshal Dhananjay Khot, who is now principal consultant, implementation of decadal vision & strategy, in space regulator IN-SPACe, also told TOI during the DefSpace symposium, that NaVIC operating with three satellites is a big setback for security forces.Indian armed forces use the navigation satellite system for logistics, mapping and operational planning. Even missiles navigate based on a country’s navigation system. Relying on a foreign navigation satellite system could pose security issues, especially during wars.India had planned to develop its own navigation system when the US denied GPS data to the country at the peak of the Kargil war with Pakistan. With the first IRNSS satellite launch in 2013, India was able to have a seven-satellite constellation completed on April 28, 2016. However, with no replacement satellites launched, India’s navigation system needs urgent attention.Besides the US’s GPS, Russia operates GLONASS, Europe runs Galileo, and China operates the BeiDou Navigation Satellite System (BDS). These three systems, like GPS, provide global coverage with constellations of around 24–35 satellites in medium Earth orbit. China’s BeiDou has more than 30 operational satellites, while Europe’s Galileo offers high-precision civilian positioning services worldwide.