The Saab JAS 39 Gripen (English: "griffin"[Nb 4][3]) is a light single-enginemultirole fighter aircraft manufactured by the Swedish aerospace companySaab. It was designed to replace theSaab 35 Draken and 37 Viggen in theSwedish Air Force (Flygvapnet). The Gripen has a delta wing and canardconfiguration with relaxed stabilitydesign and fly-by-wire flight controls. It is powered by the Volvo RM12, and has a top speed of Mach 2. Later aircraft are modified for NATO interoperability standards and to undertake in-flight refuelling.In 1979, the Swedish government began development studies for an aircraft capable of fighter, attack andreconnaissance missions to replace the Saab 35 Draken and 37 Viggen. A new design from Saab was selected and developed as the JAS 39, first flying in 1988. Following two crashes during flight development and subsequent alterations to the aircraft's flight control software, the Gripen entered service with the Swedish Air Force in 1997. Upgraded variants, featuring more advanced avionics and adaptations for longer mission times, began entering service in 2003.