Ocean-class (L12)

The Ocean class landing platform helicopter was developed for the Royal Navy of the United Kingdom to support amphibious landing operations and embark military forces. The Ministry of Defence issued an invitation to tender in February 1992, motivated by the inadequate facilities of the aviation training ship RFA Argus during operations in the Balkans. Vickers Shipbuilding and Engineering Ltd (VSEL) won the contract in May 1993, sub-contracting the construction to the civilian Kværner yard in Govan, Glasgow, to reduce costs. Fitted out by VSEL at Barrow-in-Furness, the ship was launched on 11 October 1995 and commissioned as HMS Ocean in September 1998.

The vessel was designed to deploy an Embarked Military Force of a Royal Marines Commando Group from 3 Commando Brigade, supported by four permanently embarked Landing Craft Vehicle and Personnel operated by 9 Assault Squadron Royal Marines. The aviation facilities include a flight deck and hangar serviced by helicopter lifts to operate a variety of aircraft, including Westland Apache AH1, Sea King Mk4, Westland Super Lynx, and Boeing Chinook helicopters. The carrier could transport up to 15 Harrier V/STOL aircraft in a ferry role, though it lacked a ski jump for operational launches. Propulsion is provided by two Crossley Pielstick 12-cylinder engines. The ship's sensor suite comprises a Type 997 Artisan radar, a Type 1008 Navigational Radar, and two Type 1007 Aircraft Control Radars, supported by UAT Electronic Support Measures, DLH decoy launchers, and Surface Ship Torpedo Defence. Armament consists of four 30mm DS30M Mk2 guns, four Miniguns, eight general purpose machine guns, and three Phalanx CIWS, which were removed prior to the ship's sale.

HMS Ocean undertook its first deployment in late 1998, providing humanitarian aid in Honduras and Nicaragua after Hurricane Mitch. The carrier supported Operation Palliser in Sierra Leone in 2000 and served as the task force flagship for Operation Telic during the 2003 Iraq War. Following a refit in 2007–2008, the vessel participated in the Taurus 09 deployment and supported Operation Cunningham during the 2010 volcanic ash air travel disruption. In 2011, the ship deployed for COUGAR 11 and subsequently launched Apache helicopters during operations in Libya. After serving as a security base for the 2012 London Olympics, the carrier underwent a 15-month refit, returning to active service in 2014 and becoming the Royal Navy Fleet Flagship in June 2015. In late 2016, HMS Ocean commanded U.S. Task Force 50 in the Persian Gulf region. Its final Royal Navy deployment in 2017 involved disaster relief in the Caribbean following Hurricanes Irma and Maria.

HMS Ocean was decommissioned on 27 March 2018. The Brazilian Navy purchased the ship for £84.6 million, commissioning it as the flagship Atlântico in June 2018. Initially designated as a multipurpose helicopter carrier (PHM), the Brazilian Navy redesignated the vessel as a multipurpose aircraft carrier (NAM) on 12 November 2020 to reflect its capacity to host unmanned aerial vehicles and VTOL aircraft.