Since the early days of aviation, engineers with inventive talents had to overcome tremendous challenges. From building vehicles that can fly in a controllable manner designed and flown by pioneers like Lilienthal, Wright brothers, Sperry in the beginnings, to developing todays modern comfortable and reliable vehicles for daily routine all-weather operations (Airbus, Boeing and others), there were many creative efforts to improve performance (aircraft size, endurance, speed), minimize structural weight, provide necessary thrust, and guarantee safe flight operations. Nowadays all these inventions assure the high mobility of the modern human society in a global world. The aeronautical challenges were drivers for many new technologies and methodologies that are commonly used in other industries today. In the last three decades, the requirements for the design of high-performance flight control systems that enhance automation of flight, initiated a number of ingenious technological developments. Flight control law design is one of the areas where aeronautical engineers are pioneering new technologies. During development (design and test) of flight control laws, engineers rely on mathematical models. Inevitably such models cannot mimic all aspects of a highly complex, physical plant as a modern high-performance jet airplane and its environment (atmosphere, air traffic, etc.) with absolute fidelity. The above quotation from Einstein describes the fundamental difficulty that control engineers are facing, when striving the clearance of flight control laws on basis of mathematical models.