Indian Air Force Group Captain and one of the four astronaut-designates for India's Gaganyaan human spaceflight programme.

Krishnan is one of the four Indian Air Force test pilots that ISRO selected and trained for Gaganyaan, India's first human spaceflight programme. On 27 February 2024 the Prime Minister presented astronaut wings to all four at VSSC, Thiruvananthapuram, the first time their names were made public.
The four astronaut candidates first did generic spaceflight training in Russia, including survival training in snow, water and steppe, parabolic flights, orbital mechanics and Soyuz systems. They then joined ISRO's Human Space Flight Centre for training specific to Gaganyaan.