Aircraftman (AC) or aircraftwoman (ACW) is the lowest rank in the British Royal Air Force (RAF) and the air forces of several other Commonwealth countries.
Aircraftman ranks below leading aircraftman and has a NATO rank code of OR-1. It is now a training rank only and no airmen in productive service hold this rank. Aircraftmen do not wear any rank insignia.
The rank was introduced to the RAF in January 1919, replacing the ranks of "air mechanic", "private", and "clerk" that had been introduced under Air Memorandum No 1 in March 1918. There were three grades: Leading Aircraftman (LAC), Aircraftman 1st Class (AC1) and Aircraftman 2nd Class. A similar grading existed for junior ratings in the Royal Navy.
The lowest grade was an AC2; also colloquially known as an "AC plonk".
In RAF slang, aircraftmen are sometimes called "erks".
In the Royal Canadian Air Force, the rank is known as "aviator". This was changed from private in spring 2015 when the RCAF changed the colour of its rank insignia from gold to pearl grey. It is the lowest rank in the RCAF. Prior to 1968 the rank of aircraftman was used in the RCAF as in other Commonwealth air forces.
The Royal Australian Air Force also uses both aircraftman and aircraftwoman.
In the Royal New Zealand Air Force, the rank is known as "aircraftman", regardless of the person's sex, in line with "seaman" in the Royal New Zealand Navy.