Commander Air Force's mid-rank officers' ranks are modelled on those of the Royal Navy, the term wing commander is used as a rank, and this is the equivalent of a lieutenant colonel in the army or a commander in the navy. The rank of wing commander is above that of squadron leader and below that of group captain. In the former Royal Naval Air Service, which was merged with the Royal Flying Corps to form the Royal Air Force in 1918, the pilots held appointments as well as their normal ranks in the Royal Navy, and they wore insignia appropriate to
Squadron leader it was suggested that the RAF might use the Royal Navy's officer ranks, with the word "air" inserted before the naval rank title. For example, the rank that later became squadron leader would have been air lieutenant commander. However, the Admiralty objected to this modification of their rank titles. The rank title squadron leader was chosen as squadrons were typically led by RAF majors and the term squadron commander had been used in the Royal Naval Air Service. The rank of squadron leader has been used continuously since 1 August 1919. From 1 April 1918 to 31 July 1919, the