AIRPASS was a British airborne interception radar and fire-control radar system developed by Ferranti. It was the world's first airborne monopulse radar system, the first all-digital airborne radar, and fed data to the world's first head-up display. The name is an acronym for "Airborne Interception Radar and Pilot's Attack Sight System". In the Royal Air Force (RAF) it was given the official name Radar, Airborne Interception, Mark 23, normally shortened to AI.23. AIRPASS was used on the English Electric Lightning throughout its lifetime.
A modified version, AIRPASS II, was designed for low-level flight navigation and targeting. This was originally intended for the BAC TSR.2, but when that aircraft was cancelled in 1965, it was subsequently used in the Blackburn Buccaneer. Elements of the AIRPASS design were used on many subsequent radars from Ferranti, while its head-up display was soon licensed for use in the United States where it was quickly adopted for many aircraft.
The AIRPASS system was announced to the public in late June 1958. It was initially tested on a Douglas DC-3 and later on an English Electric Canberra (WJ643) for higher speed trials, replacing the nose sections of these aircraft. After testing use, WJ643 was renamed T.Mk 11 and used as a trainer aircraft for the radar operators of the Gloster Javelin. Several further T.Mk 11 were produced, but these mounted the AI.17 from the Javelin.
It entered service on interceptor aircraft from the early 1960s. It was initially linked to the de Havilland Firestreak air-to-air missile. AIRPASS was developed by Ferranti Ltd on Ferry Road in Edinburgh. It introduced the HOTAS (Hands On Throttle-And-Stick) system whereby the radar and gun sight controls were situated on the control column and throttle lever instead of elsewhere in the cockpit, eliminating the need for the pilot to take his hands off the controls while making an interception.
The radar entered service with the RAF in 1960 in the English Electric Lightning interceptor. The next version of the system was called AIRPASS II, or "Blue Parrot", and was a system optimised for use at low-level and originally developed for the cancelled BAC TSR.2 and subsequently used in the Blackburn Buccaneer.
The radar system allowed the aircraft to find hostile aircraft. It had search and automatic track modes.
The radar of AIRPASS I weighed around 90 kg.
- Museum of Communication
- Halpenny, Bruce (2014). English Electric Canberra: The History and Development of a Classic Jet. Pen and Sword. p. 72.
- Darling, Kev (2008). English Electric/BAC Lightning Mks 1-6. Big Bird Aviation. p. 19.
- Flight Global July 1958