Vice Chief of the Air Staff (India)

The Vice Chief of the Air Staff (VCAS) is a statutory office held by the second-highest ranking officer of the Indian Air Force (IAF). Customarily held by a three-star air marshal, the VCAS is the senior most Principal Staff Officer (PSO) to the Chief of the Air Staff (CAS) - the professional head of the IAF. By duty, the VCAS has dual roles: in wartime, to oversee operational planning, capability build-up and force deployment during wartime; in peacetime, to act as an understudy to the CAS during peacetime.

Source: Wikipedia — Vice Chief of the Air Staff (India) (CC BY-SA 4.0)