In this paper, an optimal path of trajectory for inertial platform motion relative to the earth will be designed. The time dependent motion, (i.e., vertical and level mobility rates), must be designed to excite all the parameters of the system, i.e., gyro and accelerometer parameters. The criterion used for optimization is the maximization of the determinant of the observability matrix. An application of this technique to two and three parameters of an accelerometer is shown. The computer results for a four accelerometer parameters case is also given.