The trade classification of Leading Aircraftman was created on 5 April 1918 to fill a void in the Service ranks. It was granted the double-bladed propeller rank insignia of the RFC Air Mechanic 1st Class and was equivalent in rank and authority to the Army appointment of Lance-Corporal. On 1 January 1919 the rank of Aircraftman replaced the ranks of Private, Air Mechanic, and Clerk. Aircraftmen were nicknamed "Erks" (a corruption of the word 'Aircraft') by the senior ranks, which was preferred to 'other ranks' or 'troops'.