Acting pilot officer (APO[1]) is the lowest commissioned grade in the Royal Air Force.

In order to be awarded a Volunteer Reserve commission they have to complete a course run by the Officer and Aircrew Cadet Training Unit at RAFC Cranwell.

On graduation, Royal Air Force Volunteer Reserve acting pilot officers hold a full commission for one year.

However, starting in 2013 OACTU took over the duties of training acting pilot officers with a course aligned with the commissioning course of the RAF reserves.

This is worn on both the lower sleeves of the tunic or on the shoulders of the flying suit or the casual uniform.