British military aircraft designations are used to refer to aircraft types and variants operated by the armed forces of the United Kingdom.

Since the end of the First World War, aircraft types in British military service have generally been known by a service name (e.g. 'Spitfire'), with individual variants recognised by mark numbers, often in combination with a letter to indicate the role. This is in contrast to identification systems used in countries such as the United States, where an aircraft type is primarily identified by an alphanumeric designation.

The British military aircraft designations (e.g. 'Spitfire Mark V' or 'Hercules C3') should not be confused with the military aircraft registration (also known as its "serial"Westland Lysander RAF Museum) used to identify individual aircraft (e.g. XR220), nor with U.S. aircraft designations (e.g. C-5, C-17, MQ-9) or manufacturer's designations (e.g. Sikorsky S-58, Jaguar B, WS-61, AW139, WAH-64), though mark numbers were used to indicate aircraft built for other nations e.g. Hawker Hunter Mk.58 was a Hunter F.6 for the Swiss Air Force.

No designation system was introduced during World War I that covered more than the products of a single manufacturer. The Admiralty frequently referred to designs by the serial of the first aircraft of that type to be accepted for service.

The military designation system In this system, which has been used since the end of World War I, each aircraft designation consists of a name, (sometimes) a role prefix, and a mark number.

A unified official naming system was introduced in February 1918 by the Ministry of Munitions, the scheme would use classes of names related to the role. Fighter aircraft were to be animals, plants or minerals; bomber aircraft were to have geographical names; and 'heavy armoured machines' would be personal names from mythology. The classes were further divided by size of aircraft and land or sea-based, for example a three-seater sea-based fighter would be named after shellfish. Italian towns were to be used for single-seat land-based bombers.

Following the formation of the Royal Air Force (RAF) in April 1918, the Ministry of Munitions introduced a new system as Technical Department Instruction 538. They mainly followed the February 1918 scheme, but certain names already used for engines were excluded, for example birds of prey were used by Rolls-Royce for their aero-engines. The names related to zoology, geography, and mythology were withdrawn in 1927, and the Air Ministry introduced names with the initial letters relating to role, for example C for troop carriers as used by the Handley Page Clive. A further change was made in 1932 and 1939, to use more appropriate names. Fighters were to use "General words indicating speed, activity or aggressiveness", and trainer aircraft would be "words indicating tuition and places of education".

Bombers were to be named after inland towns in the British Empire, for example the Avro Lancaster and Fairey Battle (after Battle, East Sussex, the site of the Battle of Hastings). With the introduction of helicopters, these were to be named after trees but only the Bristol Sycamore was named in this scheme.

Names The name ('type name') of an aircraft type would be agreed between the Air Ministry or Admiralty and the manufacturer or importer when the order was placed. Names generally followed one or a number of patterns: Alliteration was particularly common; e.g. aircraft from Vickers-Armstrongs were given names starting with V,Vickers names starting with W were of geodesic construction. Hawker Aircraft, names starting with H, etc. This began during the First World War, when aircraft manufacturers were given an initial pairing of letters to use in the naming of their aircraft: e.g. Boulton Paul Ltd were given 'Bo'. From this, and the requirement to use the names of birds or insects for fighter aircraft, their first in-house fighter design was the Boulton Paul Bobolink. For bombers the additional requirement was a place-name, hence the Boulton Paul Bourges; and its contemporaries; the Airco DH.10 Amiens and Vickers Vimy (Bourges, Amiens and Vimy all being in France).Brew, Boulton Paul Aircraft Heavy bombers received the names of cities and towns: Short Stirling, Avro Lancaster, and Handley Page Halifax. Likewise transport aircraft also received the names of cities and towns: Avro York, Vickers Valetta, Handley Page Hastings, and Blackburn Beverley. Flying boats were given the names of coastal or port communities: Saro London, Supermarine Stranraer, and Short Sunderland. Land-based maritime patrol aircraft were named for naval explorers: Avro Anson (Admiral George Anson), Lockheed Hudson (Henry Hudson), Avro Shackleton (Ernest Shackleton), and Bristol Beaufort (Francis Beaufort). Aircraft for army co-operation and liaison and gliders were given names associated with mythological or legendary leaders; e.g.: Westland Lysander, Airspeed Horsa, General Aircraft Hamilcar, and Slingsby Hengist. A sense of irony was present when some of the names were chosen as Hengist and Horsa were the mythical leaders and founders of England when the Angles, Saxons, and Jutes invaded the British Isles in the 5th century. American aircraft, whether purchased directly or sourced under Lend-Lease, were given American-themed names following established patterns, e.g.: the Martin Baltimore and Consolidated Catalina. The American services, with the exception of the U.S. Navy, were not generally in the habit of giving aircraft names, and many British-chosen names would later be adopted; e.g.: the North American P-51 Mustang began life as the North American Mustang Mk.I with the Royal Air Force. U.S. Navy names, conversely, were being increasingly adopted by the Fleet Air Arm as 1942 and 1943 progressed, as in the case of the Grumman F4F Wildcat shedding its alternative Fleet Air Arm 'Martlet' name in favour of 'Wildcat', the original American naval name. Naval versions of aircraft not originally ordered for the Fleet Air Arm were given the prefix 'Sea', such as with the Hawker Sea Hurricane and de Havilland Sea Venom, while Seafire for the navalised Supermarine Spitfire was a contraction of 'Sea Spitfire'. Sometimes, the naval version entered service without a corresponding land-based type doing so, as with the Hawker Sea Fury and de Havilland Sea Vixen. Naval aircraft ordered as such had names with a nautical theme; e.g.: Supermarine Walrus, Blackburn Roc, and Fairey Gannet. Torpedo bombers were given 'fish' names; e.g.: Blackburn Shark, Fairey Swordfish, and Fairey Barracuda. Mythological names, particularly with an association with water were common, such as Blackburn Iris, named for the goddess of sea and sky, and Nimrod the mighty hunter, used for the Hawker Siddeley Nimrod and Hawker Nimrod (a 1930s carrier fighter). Nimrod aside, many naval fighters were named for birds; such as the Fairey Flycatcher, Fairey Fulmar, Blackburn Skua and, before the aforementioned adoption of the U.S. Navy's existing names for Fleet Air Arm aircraft of American origin, Grumman Martlet (the martlet being a heraldic bird) for the F4F fighter. Training aircraft were given names related to academic institutions: Airspeed Oxford, North American Harvard, Boulton Paul Balliol, and Fairchild Cornell. As with other American aircraft purchased, appropriate US names were used; the Harvard and Cornell universities. Alternative names for teachers were also used; De Havilland Dominie, Percival Provost, Miles Magister, and Percival Proctor. Aircraft built for one role, such as the Avro Anson or Armstrong Whitworth Albemarle, but converted to other roles, rarely changed their names. However significant changes in a design might result in a name change; the extensive redesign of the Avro Manchester from two engines to four was renamed Avro Lancaster, which was in turn renamed Avro Lincoln (initially Lancaster Mark.IV) as the design was improved, however the Lincoln had more in common with the Manchester than the late models of Spitfire did with the early versions so it was not consistent. A trend might also be followed by a manufacturer; Hawker Hurricane, Typhoon, Tornado, and Tempest. Where civilian aircraft types have been taken into service, their existing names or alphanumeric designations have often (though not always) been retained; e.g.: the Vickers VC10 or Lockheed TriStar.

The systems began to change in the immediate post-Second World War period, with the V bombers and types such as the Supermarine Scimitar. The RAF's three post-war jet-engined, swept wing strategic bombers were given names beginning with 'V' – Vickers Valiant, Avro Vulcan, and Handley Page Victor (the V bombers).

Role prefixes

+British military aircraft prefixesPrefixDescriptionExample with markAairborne (paratroop transport)Halifax A.VIIABRamphibian boat reconnaissanceSupermarine Sea Otter ABR.1AEWairborne early warningSentry AEW.1AHarmy helicopterWestland Lynx AH.7ALarmy liaisonIslander AL.1AOPairborne observation postAuster AOP.9ASanti-submarineGannet AS.1ASRair-sea rescueSea Otter ASR.IIASaCairborne surveillance and controlSea King ASaC.7BbomberVulcan B.2B(I)bomber interdictorCanberra B(I).8B(K)bomber/tankerValiant B(K).1B(PR)bomber/photo reconnaissanceValiant B(PR).1B PR(K)bomber/photo reconnaissance/tanker]]Valiant B(PR)K.1B(SR)bomber/strategic reconnaissanceVictor B(SR).2CtransportHercules C.4CCcommunications transportBAe 125 CC.3CODcourier – later carrier – onboard deliveryGannet COD.4C(PR)transport/photo reconnaissancePembroke C(PR).1Ddrone (pilotless aircraft)Shelduck D.1DW mine exploding ('directional wireless')Wellington DW.1Eelectronics (particularly electronic warfare)Canberra E.15ECMelectronic counter-measuresAvenger ECM.6FfighterTyphoon F.2FAfighter/attackSea Harrier FA.2FAWfighter, all-weatherJavelin FAW.9FBfighter-bomberSea Fury FB.11FGfighter/ground attackPhantom FG.1FGAfighter/ground attack (superseded by FG)Hunter FGA.9FGRfighter/ground attack/reconnaissancePhantom FGR.2FRfighter/reconnaissanceHunter FR.10FRSfighter/reconnaissance/strikeSea Harrier FRS.1GAground attackHunter GA.11GRgeneral reconnaissance(to 1950, superseded by MR)Lancaster GR.IIIGRground attack / reconnaissanceHarrier GR.9GTglider tugMaster GT.IIHARhelicopter, air rescueSea King HAR.3HAShelicopter, anti-submarineSea King HAS.2HChelicopter, cargoChinook HC.2HCChelicopter, communicationsSquirrel HCC.1HFhigh-altitude fighter (Spitfire only)Spitfire HF.VIIHMhelicopter, maritimeMerlin HM.1HMAhelicopter, maritime attackLynx HMA.8HRhelicopter, rescueDragonfly HR.5HThelicopter, trainingGriffin HT.1HUhelicopter, utilitySea King HU.4KtankerVC10 K.4KCtanker / cargo TriStar KC.1Llow-altitude fighter (Seafire only)Seafire L.IIILFlow-altitude fighter (Spitfire only)Spitfire LF.XVIMetmeteorological reconnaissance (superseded by W)Hastings Met.1MRmaritime reconnaissanceNimrod MR.2MRAmaritime reconnaissance and attackNimrod MRA.4NFnight fighterVenom NF.2PRphotographic reconnaissanceCanberra PR.9RreconnaissanceSentinel R.1RGreconnaissance / ground attackProtector RG.1Sstrike (nuclear capability)Buccaneer S.2SRstrategic reconnaissanceVictor SR.2STspecial transportAlbemarle ST.VITtrainingHawk T.1TFtorpedo fighterBeaufighter TF.XTRtorpedo/reconnaissanceSea Mosquito TR.33TTtarget tugCanberra TT.18TXtraining gliderCadet TX.3Udrone (pilotless aircraft) – (superseded by D)Meteor U.15Wweather research (single aircraft, withdrawn 2001)Hercules W.2

Mark numbers