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
Group captain which have a non-English air force-specific rank structure. It is usually abbreviated Gp Capt. In some air forces (such as the RAF, IAF and PAF), is used while in others (such as the RAAF and RNZAF) and sometimes, especially in historical contexts, as G/C. The rank of group captain is not correctly abbreviated as "captain". On 1 April 1918, the newly created RAF adopted its officer rank titles from the British Army, with Royal Naval Air Service captains and Royal Flying Corps colonels becoming colonels in the RAF. In response to the proposal that the RAF should use its own