Koch was initially sent to England for training and assessment, where he flew the Avro 504, the Armstrong Whitworth Siskin, and the Bristol Fighter. He then accepted a posting to the Middle East, and was attached to No. 208 Army Cooperation Squadron, RAF, at Heliopolis, Egypt. There he was operational on the Bristol Fighter, and in August and September 1929 was involved in the suppression of the Hebron riots. Whilst on leave in Australia in 1929, Koch met with Lieutenant Colonel Horace Brinsmead, Controller of Civil Aviation, who advised him to gain experience on larger aircraft. However, his application for posting to a twin-engine squadron was refused. In May 1930, the Squadron re-equipped with Armstrong Whitworth Atlas. Koch was also allowed to convert to the Vickers Vimy at No. 216 Squadron, and flew as second pilot on Vickers Victoria aircraft. He returned to Australia at the end of 1930, arriving in Melbourne on 15 December. In Egypt, Koch had continued his interest in rifle shooting and photography.