AFCAT Question Papers – Previous year question papers of AFCAT? Which books to refer for AFCAT: The Indian Air Force or IAF is one of the most important arms of Indian Defense System. It operates in the air. The main function of IAF is to protect the air space of the country and do the areal welfare. IAF was started in the year 1832 as an ancillary air force to the British Empire in India. The President of India is the supreme commander-in-chief of the armed force.