In the context of British Empire military aviation during World War I, the term half flight or half-flight was used for equivalent formations; at the time a flight was normally four to six aircraft. Hence the Mesopotamian Half Flight, the first Australian flying unit to see action, initially comprised three aircraft. After the war, the Royal Air Force and other Commonwealth air forces adopted the term section for a formation of three aircraft, while a flight was normally six aircraft. The Royal Air Force Regiment, the ground-based component of the Royal Air Force, currently employs a section structure similar to that of the British Army.