Singh was commissioned as a Pilot Officer in December 1939, after topping the Empire Pilot training course among his batch of Indian Cadets. He joined No. 1 Squadron which was then stationed at Air Force Station Kohat in the North-West Frontier Province (NWFP) and flew Westland Wapiti biplanes. The Squadron was conducting operations against the tribal forces in NWFP, in which he participated. While flying with the squadron in NWFP, Singh's Hawker Audax was shot down by the Pathans. He crashed in a dry stream in the midst of a fight between British troops and the Pathans. He was not hurt and within two weeks he was flying again in the same area. According to Singh, fighting in the NWFP prepared the squadron for the fight against the Japanese. He then was transferred to the newly-formed No. 2 Squadron for a brief period. He was transferred back to No. 1 Squadron in the rank of Flying Officer. By this time, the squadron had been re-equipped with Hawker Hurricane aircraft.