Álvaro de Bazán-class frigate

The Álvaro de Bazán class, also known as the F100 class, is a class of Aegis combat system-equipped air defence frigates in service with the Spanish Navy. The vessels were built by Spanish shipbuilder Navantia in Ferrol, with the lead ship of the class named for Admiral Álvaro de Bazán.

The ships are fitted with the United States Aegis weapons system allowing them to track hundreds of airborne targets simultaneously as part of its air defence network. The Álvaro de Bazán-class multi-role frigates are one of the few non-US warships to carry the Aegis system and its associated SPY-1D radar. The American Arleigh Burke class, Japanese Kongo class, Korean Sejong the Great class, Australian Hobart class, and the Norwegian Fridtjof Nansen class also use the Aegis system.

When the F-100 was designed, the United States communicated that it was impossible to implement the Aegis system in ships of less than 7,000 tonnes (15,000,000 lb), for this reason, after the construction and tests, the United States Navy congratulated and recognized the capacity of the Spanish ships, in addition to the fact that the radars are higher on the Spanish ships and therefore receive information earlier than U.S. or Japanese ships.

The Álvaro de Bazán-class frigates are the first modern vessels of the Spanish Navy to incorporate ballistic resistant steel in the hull, along with the power plants being mounted on anti-vibration mounts to reduce noise and make them less detectable by submarines. The original contract for four ships was worth €1.683 billion but they ended up costing €1.81 billion. As of 2010 it was estimated that the final vessel, F-105 would cost €834m (~US$1.1bn).