Invincible class

   The demise of the British fixed-wing aircraft carrier, with the cancellation of the CVA-01 fleet carrier programme in 1966, led in 1967 to a Staff Requirement for a 12 500-ton command cruiser equipped with six Sea King ASW helicopters. A redesign of this basic concept to give more deck space showed that a nine-helicopter air group was much more effective.

   A new specification resulted in a design that became known as the 19 500-ton through deck cruiser (TDC), a term used for what was essentially a light carrier design because of the political sensitivity with which politicians viewed the possibility of a carrier resurrection at the time. Despite this, the designers showed initiative in allowing sufficient space and facilities to be incorporated from the outset for a naval version of the RAF's Harrier V/STOL warplane. The designers were duly awarded for such foresight in May 1975 when it was announced officially that the TDC would carry the Sea Harrier.

   The first of the Invincible class, HMS Invincible, which had been laid down in July 1973 at the Vickers shipyard at Barrow-in-Furness, was not delayed during building. In May 1976 the second ship, HMS Illustrious, was ordered, and in December 1978 the third, HMS Indomitable, was contracted. However as a result of public disquiet, the Admiralty in placatory mood renamed the ship HMS Ark Royal. The ships were commissioned in July 1980, July 1982 and November 1985.

   The ships of the class are the largest gas turbine-powered warships in the world, with virtually every piece of below-deck equipment, including the engine modules, suitable for maintenance by exchange. During building both the Invincible and the Illustious were fitted with 7° ski-jump ramps, while the Ark Royal has a 15° ramp. In February 1982 it was announced that the Invincible was to be sold to Australia as a helicopter carrier to replace HMAS Melbourne, leaving only two carriers in British service. However, the deal was cancelled after the Falklands campaign, to the relief of the Royal Navy, as it was realised by the government that three carriers ought to be available to ensure two in service at any one time. During Operation Corporate the Invincible started with an air group of eight Sea Harriers and nine Sea King ASW helicopters. However, as a result of loses and replacements this was modified to a group of 11 Sea Harriers, eight ASW Sea Kings and two Lynx helicopters configured to decoy Exocet missiles. One of the problems was that most of the extra aircraft had to be accommodated on the deck as there was insufficient room for them in the hangar. The Illustrious was hurried through to completion in time to relieve the Invincible after the war, and went south with 10 Sea Harriers, nine ASW Sea Kings and two Sea King AEW conversions. The vessels were also fitted with two 20-mm Phalanx CIWS mountings for anti-missile defence and two single 20-mm AA guns to improve on the previous nonexistent close-in air defences. The normal air group consisted of five Sea Harriers and 10 Sea Kings (eight ASW and two AEW).

   Since the 1980s the Royal Navy has run two ships with the third undergoing a refit. The Invincible was brought to the standard of the Ark Royal, then Illustrious followed. The Ark Royal started a two-year refit in 1999.

   In recent years six RAF GR.Mk 7 Harriers have been regularly embarked for ground-attack missions under Joint Force Harrier. Illustrious has had its Sea Dart missile launcher removed to allow space for a flight extension and a new ordnance magazine. The Invincible was on station off the Adriatic in 1994 when Sea Harrier F/A. Mk 2s were first operationally deployed.

   The Invincible class light aircraft carriers will be replaced by the Queen Elizabeth class aircraft carriers. The first of the class, the Queen Elizabeth is expected to enter service with the Royal Navy in 2020.