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
History of the Royal Navy the Royal Scots Navy, taking charge of HMS "Royal Mary" on the North Sea patrol, moving to "Royal William" when she entered service in 1705, and being promoted to commodore in 1706. With the Act of Union in 1707, the Royal Scottish Navy was merged with the English Royal Navy, but there were already much larger English ships called "Royal William" and "Mary", so the Scottish frigates were renamed and , while only retained its name. After 1603 the English and Scottish fleets were organized together under James I but the efficiency of the Navy declined gradually, while corruption grew