The de Havilland Sea Vixen was a 1950s two-seat jet fighter of the Fleet Air Arm (the air wing of the Royal Navy). The aircraft was originally known as the DH.110; an aircraft designed for both the Royal Air Force (RAF) and Fleet Air Arm as an all-weather, missile-armed, and high-speed jet fighter. The Admiralty had given a requirement for a Fleet defence fighter to eventually replace the de Havilland Sea Venom. However, the RAF chose the Gloster Javelin, a rival to the DH.110, after deciding the Javelin was a cheaper and simpler aeroplane. Despite this, de Havilland continued with the project, and by the late 1950s the Royal Navy had placed an order and the aircraft entered service with the Fleet Air Arm