OVERVIEW: The Harrier T.4 belongs to the first generation of the Harrier family, a subsonic, twin-seat trainer, V/STOL (Vertical and/or Short Take-Off and Landin), aircraft operated by the Royal Air Force. Developed from the GR.3 combat variant, it shared its systems and performance while enabling instruction and conversion training.

DETAILS: The T.4 entered RAF service in 1977, built by British Aerospace during the transition to the Pegasus 11 Mk 103 engine and GR.3 upgrades. It is powered by the Rolls‑Royce Pegasus 11 Mk 103 turbofan, producing approximately 21,500 lbf of thrust. The airframe features a lengthened fuselage and taller fin to accommodate dual cockpit seating and maintain flight stability. It includes the same laser ranger and marked-target seeker (LRMTS) as the GR.3, and has a radar warning receiver. The trainer retained five to seven external hardpoints depending on configuration, and a weapons-capable nose with ADEN gun pods. Maximum speed was approximately Mach 0.97.

The “T” designation denotes a trainer variant. Compared to single-seat GR models, the T.4 added dual controls, tandem seating, modified avionics to support instruction, and an elongated fuselage. It enabled pilot conversion to advanced Harriers without modifying combat aircraft.

TYPE: V/STOL trainer and conversion aircraft

FUNCTION: The T.4 was used by RAF Operational Conversion Units to train pilots transitioning to front-line Harrier service. Its full combat-equipped fuselage allowed for realistic training with live sensor and weapon systems.

NOTE:
IOC: 1977 (T.4)
Operators: United Kingdom
Manufacturer: British Aerospace (United Kingdom)
Conflict used in: None (trainer only)

SOURCE:
British Aircraft Restoration Company: https://www.bcar.org.uk/bae-harrier ; Hawker Siddeley Harrier variants list: https://en.wikipedia.org/wiki/List_of_Harrier_variants ; Hawker Harrier variant specs: https://www.jetsofthecoldwar.co.uk/hawker-harrier/