In order to conduct this research, certain requirements for the design and simulation of concepts must be set. Accurate models of aircraft are necessary for the design of controllers and evaluation of the performance. The software architecture exhibits a multi-loop control structure in which an inner loop controller stabilizes the aircraft dynamics, while a guidance outer-loop controller is designed to control the vehicle kinematics, providing path-following capabilities. The problem of path following can be described as that of making an aircraft converge to and follow a desired spatial path, while tracking a desired velocity proﬁle that may be path dependent. Collision/obstacle avoidance is another important component of the sense and avoid system, while the on board intelligence is to monitor their health and prevent ﬂight envelope violations for safety. A UAV health condition depends on its aerodynamic loading, actuator operating status, structural fatigue. Any technique to maintain speciﬁc ﬂight parameters within the operational envelope of an autonomous aircraft falls under envelope protection. Since UAV are expected to be operated more aggressively than manned counterparts, envelope protection is very important in smart autonomous aircraft and must be done automatically due to the absence of a pilot on board. Finally, it is important to ensure that the mission planning algorithm is deterministic in terms of computation time and solution cost. This book presented diverse methods useful for all these topics.