In 1911, at the age of 49, Henderson learned to fly, making him the world's oldest pilot at that time. He formed part of the technical sub-committee of the Air Committee which helped to decide the organisation of the Royal Flying Corps, which was formed on 13 April 1912. In 1913 the control of military aviation was separated from the responsibilities of the Master-General of the Ordnance. A new Department of Military Aeronautics was established and Henderson was appointed the first director and, with the outbreak of the First World War, he took up command of the Royal Flying Corps in the Field. On 22 November 1914, Henderson was appointed General Officer Commanding the 1st Infantry Division and his chief of staff Frederick Sykes took up command in his stead. However, Henderson did not spend long commanding the 1st Infantry Division. The decision to post Henderson and replace him with Sykes was not to Lord Kitchener's liking, and he ordered a reversal of the appointments. On 20 December 1914, Henderson resumed command of the Royal Flying Corps in the Field and Sykes was once again his chief of staff.