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 air forces, such as Colonel, other air services, especially non-combat auxiliaries in Commonwealth countries, have used a variety of alternative names for equivalent ranks. The equivalent rank in the Women's Auxiliary Air Force, Women's Auxiliary Australian Air Force, Women's Royal Air Force (until 1968) and Princess Mary's Royal Air Force Nursing Service (until 1980) was "group officer". The equivalent rank in the Royal Observer Corps (until 1995) was "observer captain", which had a similar rank insignia. Group captain Group captain is a senior commissioned rank in many air forces. Group captain has a NATO rank code of OF-5, meaning that