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World War II

During the Second World War from 1941 to 1946, he served in the Royal Air Force as a radar specialist and was involved in the early-warning radar defence system, which contributed to the RAF's success during the Battle of Britain. Clarke spent most of his wartime service working on ground-controlled approach (GCA) radar, as documented in the semiautobiographical Glide Path, his only non-science fiction novel. Although GCA did not see much practical use during the war, after several years of development it proved vital to the Berlin Airlift of 1948–1949. Clarke initially served in the ranks and was a corporal instructor on radar at No. 2 Radio School, RAF Yatesbury in Wiltshire. He was commissioned as a pilot officer (technical branch) on 27 May 1943. He was promoted to flying officer on 27 November 1943. He was appointed chief training instructor at RAF Honiley in Warwickshire and was demobilised with the rank of flight lieutenant.