and intended to perform both the basic and advanced training syllabus, as well tactical training functions, as an alternative to single-engined turboprop-powered competitors. Design The S-211 is a compact two-seat shoulder-wing monoplane, possessing a full aerobatic capability. It is furnished with a retractable tricycle landing gear and is powered by a single Pratt & Whitney Canada JT15D-4C turbofan powerplant. The S-211 has been principally used as a basic trainer aircraft, the student and instructor being seated in a tandem arrangement; the front and rear cockpits are fully duplicated, the latter being elevated above the former to provide the occupant with improved forward visibility. Additionally, the aircraft was designed to perform a secondary close air support (CAS) capability, being equipped with four underwing hard points, facilitating the carriage of various armaments and other external stores, including sensor apparatus and photographic equipment for undertaking aerial reconnaissance missions. Some models feature an additional hard point on the underside of the fuselage. The airframe is largely composed of several composite materials, which includes Kevlar, Nomex and carbon fibre, while extensive use of structural bonding was made during construction. The flight controls feature manually operated push-pull rod primary controls; many other systems, such as the air brake, landing gear, compressor, and boosted ailerons, are hydraulically-actuated at a nominal operating pressure of 200 bar (3,000 psi). The electrical system consists of a 28V DC supply, being powered by an engine-driven generator, an AC supply for instruments and avionics is provided via a pair of inverters; to facilitate engine start-up and accommodate emergency situations, the aircraft is outfitted with a nickel-cadmium battery unit. For greater crew comfort, an automatically adjusting environmental control system is installed; it uses a non-ozone-depleting vapour cycle for cooling, which is combined with bleed air drawn from the engine for heat and pressurisation alike. The avionics of the S-211 were designed to be customisable, allowing the manufacturer to accommodate a customer's various mission requirements. In a typical configuration, the aircraft would be provided a VHF/UHF communications suite, multiple navigation systems, such as an attitude and heading reference system (AHRS), horizontal situation indicator, automatic direction finding (ADF), VHF omnidirectional range and instrument landing system (VOR-ILS), a tactical air navigation system (TACAN) and identification friend or foe (IFF) transponder. Operators can choose to have their S-211s outfitted with modern glass cockpits. The S-211's single JTI5D-4C engine provides a maximum thrust output of 11.12 kN (2,500