mm anti-aircraft autocannons. During 1986–1989, she underwent a major refit, with several changes to increase the ship's aircraft operating efficiency. The angle of the ship's ski-jump was increased to 12 degrees. Her hangar was modified to allow more aircraft (nine Sea Harriers and twelve Sea Kings) to be accommodated below. The ship's overall length increased to . Additional command facilities were fitted and accommodation for another 120 people (aircrew and command staff) was added. The ship's magazines were enlarged, allowing Sea Eagle anti-ship missiles for the carrier's Sea Harriers to be carried, while also increasing the number of torpedoes carried for the ship's helicopters. Three Thales 30 mm Goalkeeper CIWS replaced the Phalanxes. Type 996 air-sea search radar replaced the Type 992 radar, with Type 2016 sonar replaced the Type 184. In 2000, Invincible was subject to further modifications to allow her to operate Harrier GR.7s in a ground-attack role. The Sea Dart launcher was removed and the ship's flight deck was enlarged. History Invincible was ordered from Vickers Shipbuilding and Engineering on 17 April 1973, and was laid down at Vickers' Barrow-in-Furness on 17 April 1973. The ship's construction was delayed by design changes and industrial action, and Invincible was not launched until 3 May 1977. The ship was launched by Elizabeth II. She was accepted into Royal Navy service on 19 March 1980 and after trials, formally commissioned on 11 July 1980. More trials and work-up followed for the ship and her air wing followed before she was declared operational on 19 June 1981, joining the fleet's other carrier Hermes in service. Invincibles initial air wing consisted of 801 Naval Air Squadron, equipped with five Sea Harriers and 820 Naval Air Squadron, equipped with Sea King anti-submarine helicopters. In August–September 1981, Invicible took part in the NATO naval exercises "Ocean Venture" and "Ocean Safari". Proposed sale and Falklands War On 25 February 1982, after several months of negotiations, the Australian government announced that it had agreed to buy Invincible for £175 million (285 million A$) as a replacement, under the name , for the Royal Australian Navy's . Australia planned to make minimal changes to the carrier, adding more fuel and replacing some of the ship's computers. Initially at least, it was planned to operate helicopters only. The sale was confirmed by the Ministry of Defence. On 2 April 1982, however, Argentina invaded the Falkland Islands. Three days