In September 1941 Smith formally enlisted in the Royal Air Force and received service number 80463. He began his instruction with Initial Training Wing in Bulawayo, and after six weeks transferred to Elementary Flying Training School at Guinea Fowl, just outside Gwelo. The majority of the men he trained alongside were Australians, and many others were British. Smith was glad to find himself in a course that would ultimately lead to flying fighters as opposed to bombers, since at Guinea Fowl he learned to pilot Tiger Moths, then Harvards. He was also pleased to have been posted only a half-hour car journey from Selukwe. Late in the course he was picked out to undergo instruction as an officer cadet, which meant he was transferred to Thornhill, another Gwelo airbase. He passed out in September 1942 with the rank of pilot officer; his training in Southern Rhodesia had taken a year in all. Smith hoped to be posted to Britain at the end of his training, and was initially told that this was going to happen, but he was instead sent to the Middle East. He was despatched to Idku, a small RAF base near Cairo, in late 1942, from where he was posted to an operational training unit based at Baalbek in Lebanon. He spent six weeks there, flying over much of the Levant in a Hawker Hurricane fighter, before being posted to No. 237 (Rhodesia) Squadron to begin active service, again piloting Hurricanes. The squadron was stationed near the Iranian capital of Tehran when Smith joined it, but it almost immediately transferred to Kirkuk in Iraq, to help guard the oil wells and pipelines there. In March 1943, it was again committed to the Western Desert Campaign in North Africa, having previously served there during 1941–1942, and Smith served on this front as a Hurricane pilot. He was promoted to flying officer on 25 March 1943. On 4 October 1943, Smith took off from Idku at dawn in a Hurricane Mk IIC to escort a shipping convoy. Light was extremely poor, and Smith's throttle malfunctioned; he failed to take off quickly enough to clear a blast wall at the end of the runway. The undercarriage of the aircraft scraped against some sandbags on the wall, causing Smith to lose control of the plane and crash. The shoulder straps on his harness, built to withstand stress of up to , snapped, and his face was smashed against the Hurricane's gyrosight. Smith suffered serious facial injuries, and broke his jaw, a leg and a shoulder.