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. In RAF slang, aircraftmen are sometimes called "erks".
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.