The Pacific Aerospace Corporation CT/4 Airtrainer series is an all-metal-construction, single-engine, two-place with side-by-side seating, fully aerobatic, piston-engined, basic training aircraft manufactured in Hamilton, New Zealand.
Pacific Aerospace Corporation predecessor, AESL, derived the CT/4 from the earlier four-seat prototype Victa Aircruiser, itself a development of the original Victa Airtourer two-seat light tourer, 172 of which had been built in Australia from 1961 to 1966 before the rights to the Airtourer and Aircruiser were sold to the New Zealand company AESL, which built a total of 80 Airtourers at their factory at Hamilton in the 1970s.
In 1971, the Royal Australian Air Force had a requirement for the replacement of the CAC Winjeels used as basic trainers at RAAF Point Cook. AESL's chief designer, P W C Monk, based the new aircraft on the stronger airframe of the Aircruiser. Externally the CT/4 differs from the Airtourer and Aircruiser designs by its larger engine and the bubble canopy—designed in an aerofoil shape. Structurally there are changes to the skin and upgrading of the four longerons in the fuselage from sheet metal to extrusions.
The CT/4 prototype first flew on February 23, 1972. Two prototypes were built, and on 1 March 1973 AESL became New Zealand Aerospace Industries Ltd. Production was launched against an order for 24 from the Royal Thai Air Force. The type was then selected as the primary trainer for the Royal Australian Air Force. The 64th machine was the first CT/4B, with detail improvements, mostly in instrumentation. The CT/4B was ordered by the Royal New Zealand Air Force (19) and 14 were ordered ostensibly by a Swiss company, Breco Trading Co, on behalf of a Swiss flying club. Breco was discovered to be a sanctions busting front for the Rhodesian Air Force. These aircraft were then embargoed by the New Zealand government after being built and spent six years in storage before being sold to the Royal Australian Air Force. This caused financial difficulties for the manufacturer, which lead to the firm re-emerging as the Pacific Aerospace Corporation.
For several years Airtrainer production ceased, although the type remained nominally available for orders. In 1991, in an attempt to win a lucrative United States Air Force contract, two new developments of the CT/4 airframe were flown—the CT/4C turboprop and the CT/4E with a 300 hp piston engine, a three-bladed propellor, 100 mm longer fuselage and wing attachments moved rearwards. Neither attracted production orders at the time but, in 1998, CT/4E production commenced with orders for the Royal New Zealand Air Force for 13 and Royal Thai Air Force for 16. Both nations used the CT/4E to replace their earlier model CT/4A and B.