demo EMB-312 aircraft was modified as proof-of-concept prototype. The aircraft featured a 1.37-m (4.49-ft) fuselage extension with the addition of sections fore and aft of the cockpit to restore its centre of gravity and stability, a strengthened airframe, cockpit pressurization, and stretched nose to house the more powerful PT6A-67R (1.424 Shp) engine. The PT-ZTW, s/n 161, flew in September 1991. Two new prototypes EMB-312H with the PT6A-68A (1.250 Shp) engine were built in 1993. The second prototype PT-ZTV, s/n 454 (later PP-ZTV) flew for the first time in May 1993. It featured a reinforced wing skin developed for the model F, an improved glass cockpit, full pressurization system, electrical swing back canopy opening and zero-zero ejections seats. The third prototype PT(PP)-ZTF, s/n 455, flew in October 1993, as a twin of the s/n 454. The EMB-312H's design later served as a starting point for the EMB-314 Super Tucano, dubbed the ALX, and adopted by the Brazilian Air Force as the A-29. Design Many features of the EMB-312 became standard in later basic-training aircraft designs. It was the first turboprop trainer developed from the beginning with military jet capability. A Martin-Baker Mk8L was fitted. It was Embraer's first aircraft with tandem seats designed with a raised rear seat optimized for an uninterrupted view from the rear cockpit and a frameless bubble canopy for unobstructed visibility. Major aircraft features include an automatic torque control system and the jet-like, single-lever throttle which combined both engine power and propeller pitch, assuring smooth and rapid acceleration and deceleration. The aircraft is fitted with a retractable tricycle undercarriage with steerable nosewheels, allowing a fairly large crab angle during cross-wind landing. The reverse pitch control with which the aircraft is fitted allows the constant-speed mechanism to be manually overridden to reverse the blade pitch angle, thus providing excellent ground-handling characteristics, helping to slow down the plane to shorten the landing run. This control also allows the aircraft to back up on its own during taxiing. High manoeuvrability, stability at low speeds, and four underwing pylons providing for up to of ordnance, allow the training aircraft to engage in tactical bombing campaigns in low-intensity conflict or counterinsurgency environments and in counternarcotics interceptions. The type can carry up to of fuel internally; additionally, two fuel tanks of can be fitted to underwing weapon stations for extended endurance, enabling up to nine flight hours. Operational history Angola The National Air