High Quality Content by WIKIPEDIA articles! The term used in the Royal Air Force to refer to all ranks below commissioned officer level is Other Ranks (ORs). It includes Warrant Officers, non-commissioned officers (NCOs), and airmen. Upon the formation of the Royal Air Force in 1918, rank titles and badges for ORs were adopted from the British Army, specifically the Royal Flying Corps (RFC). The RFC ranks of Warrant Officer Class I, Warrant Officer Class II, Flight Sergeant, Sergeant, and Corporal were directly adopted, although the four-bladed propeller above the Sergeants' and Flight Sergeants' chevrons was dropped. The double-bladed propeller used as the badge of rank for an RFC Air Mechanic 1st Class was introduced as the trade classification badge for Leading Aircraftman. The rank of Aircraftman replaced the RFC rank of Air Mechanic 2nd Class.