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Flight sergeant (Flt Sgt, F/Sgt, or FS) is a senior non-commissioned rank in the British Royal Air Force and several other air forces which have adopted all or part of the RAF rank structure. It is equivalent to a staff sergeant in the British Army and has a NATO rank code of OR-8 
The rank was devised in the British Royal Flying Corps (RFC) in 1912 and passed to the Royal Air Force (RAF), on its formation in 1918. RFC flight sergeants wore a four-bladed propeller between the chevrons and the crown.
On 1 July 1946, aircrew flight sergeants were redesignated Aircrew I and replaced their chevrons with three six-pointed stars within a wreath and surmounted by an eagle and a crown. This proved unpopular however, and in 1950 they reverted to their old rank and badge, although Flight Sergeants Aircrew wear an eagle between chevrons and crown. Flight Sergeants in ground trades wear only a crown above the three chevrons.
Between 1950 and 1964, the rank of Chief Technician was equivalent to flight sergeant and was held instead of it by technicians, but now chief technician is a junior rank (still held only by technicians), although classified by NATO in the same grade.
Apart from the RAF, the rank of Flight Sergeant is also used by many Commonwealth air forces, including the Royal Australian Air Force, the Royal New Zealand Air Force, the Sri Lankan Air Force, the Ghana Air Force, the Bangladesh Air Force, the Sri Lanka Air Force, the South African Air Force and the Air Force of Zimbabwe. It was also used in the former Royal Rhodesian Air Force. In Canada, since the unification of the Canadian Forces in 1968, this rank has been replaced by Warrant Officer though the rank is still used by the Royal Canadian Air Cadets. The rank is also used in the Irish Air Corps where it is equivalent to the Irish Army rank of Company Sergeant. The Flight Sergeant rank in the Indian Air Force was replaced with the rank of Junior Warrant Officer (JWO), which ranks below a Warrant Officer and above a Sergeant.
In the RAF, the rank insignia is three downward pointing chevrons below a crown and flight sergeants are usually addressed as "Flight" and are never addressed by the junior rank of "Sergeant".
Flight Sergeant is also used in many cadet organizations around the world, such as the Air Training Corps, Combined Cadet Force (RAF Section), the Australian Air Force Cadets and the Royal Canadian Air Cadets.
- STANAG 2116 Edition 6 (Annex F2)