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Invincible class aircraft carrier

See also HMS Invincible

The Invincible class aircraft carrier is a design currently in use by the Royal Navy. There are three carriers of this class in operation - the HMS Invincible (R05, 1980), the HMS Illustrious (R06, 1982) and the HMS Ark Royal (R07, 1985 (initially she was to be the Indomitable)).


The sixth (and current) HMS Invincible.

The original class design was for a 12,500 ton escort carrier as a complement to the much larger CVA fleet carrier project. The CVA was cancelled in 1966 and the escort carrier design was reworked for a ASW cruiser with six helicopters and command capability. The helicopter load was then increased to nine and the vessel was again redesigned into a 19,500 ton carrier. To avoid using the expensive word carrier the design was called a "through-deck cruiser". The successful development of the Sea Harrier meant that the plan was reworked again to include a small complement of these STOVL aircraft. In order to launch the Harrier from its comparatively short flight deck of 170m, a 'ski-jump' was included in the design of the ships, with the slope initially set at 7 for Invincible and Illustrious and 12 for Ark Royal. The class also has a secondary role as an helicopter carrier, or LPH.

The ships are armed with a variety of weapons. As built, they had two 20mm Oerlikon GAM-B01 guns, which they retain, and the Sea Dart surface-to-air missile. The Sea Dart system has been removed from all ships of the class in order to allow the flight deck to be exptended, and magazines suitable for weapons used by the Harrier GR7 to be added to the ship. Because of lessons learnt during the 1982 Falklands War, CIWS guns were added to the design. Illustrious having them fitted at the last minute before commissioning, Ark Royal had them added as a normal part of the building process, and Invincible had them fitted during her first overhaul after the Falklands. Invincible and Illustrious have three Goalkeeper CIWS systems, whereas Ark Royal has three Phalanx CIWS systems. Electronic countermeasures are provided by a Thales jamming sytem and ECM system. Sea Gnat launchers provide for chaff or flare decoys.

Prior to 1982, Invincible's airgroup consisted purely of Sea King HAS1 anti-submarine aircraft and Harrier FRS1 aircraft. Typically, nine Sea Kings, and four or five Sea Harriers were embarked. This was due to the fact that the originally envisioned mission for the ships was to provide the heart of ASW hunter-killer groups in the north Atlantic during a war against the Soviet Union. In that context, the main weapon of the carrier would not be its fighter aircraft, but its ASW helicopters. The fighters were on board to shoot down the occasional Soviet maritime patrol aircraft nosing around the ship and its escorts.

The Falklands changed all of that, since it proved that Britain still needed to retain the capability to use carrier airpower in its traditional role of power projection, both over land, and against enemy fleets (the Falklands nearly saw the first carrier vs carrier battle since WWII). The Falklands had seen Invincible, and the other aircraft carrier deployed, the larger and older HMS Hermes filled to the gunwales with both the air defence variant of the Harrier, and the Royal Air Force Harrier GR3 ground attack variant of the aircraft, along with ASW helicopters. The RAF Harriers proved to be a temporary aberration at the time, but a permanent addition to the usual airgroup was made due to lessons learnt during the war. That addition was a new type of Sea King, an Airborne Early Warning or AEW version. Illustrious carried the first examples of the type when it was rushed south in the aftermath of the Falklands to relieve Invincible of its guard duty around the islands. In the aftermath of the Falklands, the typical airgroup was 3 AEW Sea Kings, 9 ASW Sea Kings and 8 or 9 Sea Harriers.

Other improvements were made to the class during the 1980s and early 1990s, with probably the most important being the increase of the ski jump angle on Invincible and Illustrious to match the 12 slope of Ark Royal.

In more recent years, three other changes have occurred. One of those was the removal of the Sea Dart system, making the ships a great deal more like pure aircraft carriers, than the cross between cruisers and aircraft carriers that they were originally built as. It is quite surprising how much the removal of the SAM system alters the lines of the ships when viewed from the front. In company with that, the ships were fitted to routinely handle RAF Harrier GR7's, making those aircraft a routine part of the airgroup for the first time. Since then, the ships have all been fitted to handle the new Merlin helicopters. The HM1 variant of the Merlin is replacing the HAS6 variant of the Sea King in the carrier-borne ASW role. Since the adding of the RAF Harrier facilities, typical deployments have included 7 or 8 of those aircraft, pushing the ASW Sea Kings onto the carrier's escorting ships.

The two most recent wartime deployments of the class have seen them in their secondary LPH role, as it was officially judged that Harriers could provide no useful role in the missions. During those deployments, the class has embarked RAF Chinook helicopters, in lieu of their fixed wing complement.

In the next few years, the Sea Harrier is to be retired, with the three squadrons that use the type being disbanded between early 2004 and 2006. After that, RAF Harriers will make up all of the fixed wing aircraft that operate on board the ships. Officially, Invincible will decommission in 2010, Illustrious in 2012, and Ark Royal in 2015, as two new, much larger aicraft carriers are introduced into service to replace the ships. However, there are persistent rumours that Invincible will be retired early in 2006 to save money, and that one of the ships upon decommissioning will be converted into a full LPH to complement HMS Ocean in that role.

Whatever the truth of those rumours, it is undisputed that the ships have given fine service to the Royal Navy during their careers. Invincible played a large part in winning the largest naval war since WWII, and they have kept Royal Navy fixed wing aviation alive through a very lean period.