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 ranking officers that may fly a command flag. The flag may be depicted on the officer's aircraft or, should the squadron leader be in command, the flag may be flown from a flagpole or displayed on an official car as a car flag. If the squadron leader is in command of a numbered squadron, then the number of the squadron is also shown on the flag. The rank of squadron leader is also used in a number of the air forces in the Commonwealth, including the Bangladesh Air Force (BAF), Ghana Air Force, Indian Air Force (IAF), Sri Lanka Air