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
Marshal of the air force held once and is currently retained only on paper. China also does not use a marshal rank, preferring first class general ("kong jun yi ji shang jiang") which has never been held by an air force officer and was abolished in 1994. Spain uses the equivalent rank of captain general of the Air Force which is held only by HM King Felipe VI. A marshal of the air force is mentioned in Roald Dahl's book "The BFG". Dahl himself was a Royal Air Force officer during World War II. Marshal of the air force Marshal of the air force is