With the rapid development of fiber-optic gyroscope in china
the strapdown fiber-optic gyro inertial navigation system is widely used.Compass method for initial alignment is studied and the improvement is proposed for SINS on stationary base with unknown azimuth and horizontal attitude.Four-step initial alignment method show in classic has been simplified into three steps which are horizontal alignment
azimuth coarse alignment and compass alignment.The initial alignment test with the new method has demonstrated that the alignment can assure precision and reduce alignment time.