page_title: Airborne Interception radar
section_title: AI.24
hierarchical_section_title: Airborne Interception radar / Post-war systems / AI.24
caption_attribution_description: English: Panavia Tornado F3 a twin-engine, variable-sweep wing combat aircraft, in the National Museum of Flight in East Fortune, East Lothian, Scotland. Museum Number EF.2005.75 Nederlands: Panavia Tornado F3, een tweemotorig gevechtsvliegtuig met beweegbare vleugels, , in het National Museum of Flight in East Fortune, East Lothian, Schotland.
context_page_description: Airborne Interception radar, or AI for short, is the British term for radar systems used to equip aircraft in the air-to-air role. These radars are used primarily by Royal Air Force and Fleet Air Arm night fighters and interceptors for locating and tracking other aircraft, although most AI radars could also be used in a number of secondary roles as well. The term was sometimes used generically for similar radars used in other countries.
  The term was first used circa 1936, when a group at the Bawdsey Manor research center began considering how to fit a radar system into an aircraft. This work led to the Airborne Interception Mk. IV, the first production air-to-air radar system. Mk. IV entered service in July 1940 and reached widespread availability on the Bristol Beaufighter by early 1941. The Mk. IV helped end the Blitz, the Luftwaffe's night bombing campaign of late 1940 and early 1941.
  Starting with the AI Mk. VII, AI moved to microwave frequencies using the cavity magnetron, greatly improving performance while reducing size and weight. This gave the UK an enormous lead over their counterparts in the Luftwaffe, an advantage that was to exist for the remainder of World War II.
context_section_description: The final radar in the UK series of AI designs to see deployment was the Mark 24, better known as "Foxhunter". Foxhunter was developed for the Panavia Tornado ADV, an interceptor development of the Tornado that provides long-range defense against bomber-like targets. Development of the ADV began in 1976 and the radar system contract was eventually won by a curious combined bid; Marconi and Elliot Automation would provide most of the design, while Ferranti built the transmitter section and Antenna Platform.
  The first test articles were flight tested in 1981 in the nose of a Hawker Siddeley Buccaneer. Further development slowed, and the radar was still not ready for service by 1987, although the aircraft itself was now rolling off the production lines. In place of the radar a concrete ballast plug had to be installed in early Tornado ADVs, where it was jokingly known as the "Blue Circle radar", a pun referring to the Ministry of Supply's rainbow codes, and a local brand of concrete.
  Foxhunter finally entered service in the late 1980s and early 1990s, by which time the older Skyflash missiles were in the process of being replaced by the new AMRAAM. This led to a further series of problems as the radar was adapted to fire this missile. Several mid-life upgrades have also been worked into the Foxhunter program to improve performance. These upgraded versions remain in service with the Royal Saudi Air Force's Tornado F.3's as of 2014.
caption: The Foxhunter used a cassegrain reflector which gives the "dish" its unique conical shaping.
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