been reflected in increasingly sophisticated advanced trainers. As the costs of developing new aircraft have risen in real terms, it has become more likely that fewer aircraft will be designed specifically for the training role. The advanced trainer was often seen as a stepping stone by most nations in developing a fast jet design and manufacturing capability. With increasing costs, even major air forces will have difficulty reaching the economies of scale to justify development of new advanced trainers. Nations will be required to continue to push the modernisation of existing aircraft (some such as the Hawk dating from the 1970s) or co-operate in the development and procurement of advanced training aircraft. Furthermore, they must better utilise funding available by developing aircraft with an enhanced combat capability by producing operational single-seat variants, and better utilise aircraft on inventory incorporating operational systems either within the aircraft or as external pods. The trend of programmable electronic systems and datalinks is likely to continue with the possibility that ground-based radar systems and processing systems will allow advanced training aircraft to function as if they truly had onboard radar systems, with the cockpit closely replicating the look and feel of an air force's more capable aircraft for maximum familiarity. Programmable engine management and fly-by-wire flight control systems will allow an aircraft to mimic the flight characteristics of frontline aircraft with actual performance being restricted to a pilot's level of ability, with more power and greater agility becoming available as a pilot's skill improves. Training is now also carried out on ground-based simulators. Historical Early trainers were often sport aircraft or obsolete combat aircraft. The French used a graduated system in which a pilot learned in progressively more capable aircraft, starting with aircraft that had been modified to prevent them from flying – called rouleurs or penguins. Pilots who had mastered ground handling would then graduate to lower powered two seaters, before finishing on obsolete fighters. The supply of obsolete aircraft proved inadequate and production of Caudron G.III, Nieuport 83 and other types specifically for training was undertaken. In the United Kingdom, a different training system was used, although it too started out with obsolete aircraft before the Avro 504 and Airco DH.6 became the primary trainers, supplemented until the end of the First World War with obsolete combat aircraft for advanced training. To train the many potential aviators coming from Canada and the US,