a noncommissioned officer in the British Royal Air Force.

Airman Basic (U.S. Air Force)

Aircraftman (AC), or Aircraftwoman (ACW), is the lowest rank in the Royal Air Force, ranking below Leading Aircraftman and having a NATO rank code of OR-1. The rank was introduced on the formation of the RAF in 1918, replacing the Royal Flying Corps rank of Air Mechanic 2nd Class. There used to be two grades: Aircraftman 1st Class (AC1) and Aircraftman 2nd Class (AC2; also colloquially known as an "AC plonk").