Air commodore is never shortened to Commodore, which is a rank in various naval forces. Air commodore is a one-star rank and the most junior air officer rank, being immediately senior to group captain and immediately subordinate to air vice-marshal. It has a NATO ranking code of OF-6 and is equivalent to a commodore in the Royal Navy or a brigadier in the British Army or the Royal Marines. Unlike these two ranks, however, it has always been a substantive rank. Additionally, air commodores have always been considered to be air officers whilst Royal Navy commodores have not since the Napoleonic Wars
Captain (Royal Navy) Captain (Royal Navy) Captain (Capt) is a senior officer rank of the Royal Navy. It ranks above commander and below commodore and has a NATO ranking code of OF-5. The rank is equivalent to a colonel in the British Army and Royal Marines, and to a group captain in the Royal Air Force. There are similarly named equivalent ranks in the navies of many other countries. In the Royal Navy, the officer in command of any warship of the rank of commander and below is informally referred to as "the captain" on board, even though holding a junior rank, but