In 1904, Sykes's interest in aviation was first demonstrated when he obtained a ballooning certificate whilst being attached to the Balloon Section of the Royal Engineers. He was restored to the establishment of the 15th Hussars on 22 September 1904. He joined the Intelligence Staff at Simla in India in 1905 before attending Staff College, Quetta in Autumn 1908. He was promoted to captain on 1 October 1908. In 1910 Sykes commenced flying lessons at Brooklands which led to him being awarded Royal Aero Club certificate No. 96 in June 1911. On 25 February 1911 Sykes was posted as a staff officer to the Directorate of Military Operations at the War Office. As a firm believer in the importance of wartime aerial reconnaissance, he was chosen to join the sub-committee of the Committee of Imperial Defence which was given the task of investigating the use of aircraft.