By 1967, the F-111 had entered service and demonstrated the practical advantages and solutions to the technical problems of a swing-wing design. On 7 August 1968, the OKB was officially tasked with investigating a variable geometry wing for the T-6. The resulting "T-6-2I" first flew on 17 January 1970 with Ilyushin at the controls. The subsequent government trials lasted until 1974, dictated by the complexity of the on-board systems. The day or night and all-weather capability was achieved – for the first time in Soviet tactical attack aircraft – thanks to the "Puma" nav/attack system consisting of two "Orion-A" superimposed radar scanners for nav/attack, a dedicated "Relyef" terrain clearance radar to provide automatic control of flights at low and extremely low altitudes, and an "Orbita-10-58" onboard computer. The crew was equipped with Zvezda K-36D ejection seats, allowing them to bail out at any altitude and flight speed, including during takeoff and landing. The resulting design with a range of and payload of was slightly smaller and shorter ranged than the F-111.