Warrant officer
The Royal Air Force first used the ranks of warrant officer class I and II as inherited from the Royal Flying Corps. It first used the rank badges of the Royal coat of arms for WOI and the crown for WOII. Until the 1930s, these ranks were often known as sergeant major first and second class. In 1939, the RAF abolished the rank of WOII and retained just the WOI rank, referred to as just warrant officer (WO), which it remains to this day. The RAF has no equivalent to WO2 (NATO OR-8), an RAF WO being equivalent to WO1 (NATO OR-9) and wearing the same badge of rank, the Royal coat of arms. The correct way to address a warrant officer is "sir" or "ma'am" by airmen and "mister or warrant officer -surname-" by officers. Most RAF warrant officers do not hold appointments as in the army or Royal Marines; the exception to this is the station warrant officer, who is considered a "first amongst equals" on an RAF station. Warrant officer is the highest non-commissioned rank and ranks above flight sergeant.