United Kingdom military aircraft registration number, known as its serial number, or tail code is a specific aircraft registration scheme used to identify individual military aircraft belonging to the United Kingdom (UK). All UK military aircraft display a unique serial number, allocated from a unified registration number system, maintained by the Air Section of the Ministry of Defence (MoD Air). The same unified registration system is used for aircraft operated by the Royal Air Force (RAF), Fleet Air Arm (FAA), and Army Air Corps (AAC). Military aircraft operated by government agencies and civilian contractors (for example QinetiQ, AirTanker Services, Babcock International) are sometimes also assigned registration numbers from this system.
When the Royal Flying Corps (RFC) was formed in 1912, its aircraft were identified by a letter/number system related to the manufacturer. The prefix 'A' was allocated to balloons of No.1 Company, Air Battalion, Royal Engineers, the prefix 'B' to fixed-wing aeroplanes of No.2 Company, and the prefix 'F' to aeroplanes of the Central Flying School (CFS).[1] The Naval Wing used the prefix 'H' for seaplanes ('Hydroaeroplanes' as they were then known), 'M' for monoplanes, and 'T' for aeroplanes with engines mounted in tractor configuration.[1] Before the end of the first year, a unified aircraft registration number system was introduced for both Army and Naval (Royal Naval Air Service) aircraft.
The registration numbers are allocated at the time the contract for supply is placed with the aircraft manufacturer or supplier.
In an RAF or FAA pilot's personal service log book, the registration number of any aircraft flown, along with any other particulars, such as aircraft type, flight duration, purpose of flight, etc., is entered by the pilot after every flight, thus giving a complete record of the pilot's flying activities and which individual aircraft have been flown.