This thesis will present a design of a guidance and control system to use on aircrafts, primarily on UAVs. One control method for heading control and two for pitch and altitude control will be investigated. The control methods are Proportional-Integral-Derivative (PID) and sliding mode control. PID will be tested on both heading and pitch and altitude control, while sliding mode will only be applied to pitch and altitude. There will be presented a path-following method, Line of Sight, for heading guidance and a kinematic controller for altitude reference. The presented methods are implemented in Matlab Simulink while the aircraft model used comes from the flight simulator X-Plane. X-Plane is also used to visualize the performance of the autopilot design.PID and sliding mode control are tested in four different scenarios to investigate which controller who has the best performance. After the simulations, it was observed that the PID had better performances than sliding mode control.