It is equivalent in concept to a flag officer in navies and a general officer in armies and marine corps. However, in the British Armed Forces, while an air commodore is an air officer, his Royal Navy equivalent (commodore) is not considered a flag officer, nor is his British Army or Royal Marines equivalent (brigadier) considered a general officer. However, in 1919 when the RAF introduced its air officer ranks, the equivalent army rank was brigadier-general, which was a general officer rank until its abolition in 1922.