The Vice Chief of the Air Staff (VCAS) is the deputy to the Chief of the Air Staff of India and second-highest ranking officer of the Indian Air Force. The VCAS is a PSO (Principal Staff Officer) at Air Headquarters at New Delhi. In the event that the Chief of Air Staff (CAS) is absent or is unable to perform his duties, the VCAS assumes the duties and responsibilities of the CAS. The VCAS is normally held by an officer of three star rank and is held by an air officer of the rank of Air Marshal.