In this paper, we presents the general three-dimensional guidance laws. With the aid of the modified polar coordinate, the expression of relative dynamics between target and missile becomes simple, and the constructed guidance law is intuitive and naive. Furthermore, a phase plane method is used to analyze the capture condition of the corresponding guidance law. The result is not restricted to time-invariant navigation constant. For a nonmaneuvering target or a maneuvering target but with known acceleration, it can be seen that only range rate divided by range and the rate of the magnitude of the unit vector along line of sight are related to the intercept condition.
