After a short spell of flying at the Northern India Flying Club, Lahore, he was selected for the Indian Air Force and joined the services as Pilot Officer on 30 November 1940. On completion of his training, he was posted to No.1 Squadron in August 1941. In March 1946 Mehra was selected to serve as the Indian Air force representative at the Joint Chiefs of Staff in Australia, an organization set up to provide administrative and logistics support to the British Commonwealth Occupation Forces located in Japan. In view of the nationalization of the armed forces, he was recalled and posted in February 1947 as the Chief Ground Instructor at the No.1 Advanced Flying School Ambala, to replace the RAF officer who was returning home. In August 1947, he was promoted to the rank of Wing Commander and posted as Commandant of the Elementary Flying Training School at Jodhpur. On promotion to the rank of Air Vice-Marshal in August 1963, he took over as AOC in Chief Maintenance Command, in which capacity he served during the 1965 War. In January 1968 he was awarded the PVSM, and promoted to Air Marshal in March 1968. Soon thereafter he was posted as Deputy Chief of Air Staff, Air Headquarters. In early 1971, he was deputed as Chairman of Hindustan Aeronautics Limited, Bangalore. On 15 January 1973, he returned to Air Headquarters, designated as the new Chief of Air Staff, succeeding Air Chief Marshal PC Lal. Air Chief Marshal Mehra relinquished the post to Air Chief Marshal Hrushikesh Moolgavkar on 31 January 1976, on completion of his tenure.
Post-Air force career
After his retirement, he represented India at a UNESCO meeting in Paris as deputy leader of India's team. He was the recipient of Padma Vibhushan in January 1977. He went on to serve as the Governor of Maharashtra from 3 November 1980 to 5 March 1982. This was followed by his posting as Governor of Rajasthan from 6 March 1982 to 4 November 1985. Air Chief Marshal Mehra was elected President of the Indian Olympic Association in 1975, and was responsible for the hosting by India of the 1982 Asian Games. From 1978 to 1980 he was President of the Asian Games Federation, currently known as the Olympic Council of Asia, and continued to be the Honorary Life President of the Olympic Council of Asia. He was an honorary life member of the Durand Football Tournament Society, which organizes the Durand Cup. In January, 2010, his autobiography, Memories: Sweet and Sour, was released by M. Hamid Ansari, Vice President of India in New Delhi. He was Chairman, Board of Advisors of Centre for Air Power Studies In 2012, he was living in Delhi, and was the oldest living student of Panjab University, Chandigarh. He died on 8 November 2015 at the age of 96.
Works
Memories Sweet And Sour by Air Chief Marshal OP Mehra. KW Publisher, 2010..
