Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS) technologies have been widely used in a variety of positioning and navigation applications. Both systems have their unique features and shortcomings. Therefore, the integration of GNSSS with INS is now critical to overcome each of their drawbacks and to maximize each of their benefits. The integration of GPS/GNSS with INS can be implemented using a Kalman filter in such modes as loosely, tightly and ultra-tightly coupled. In all these integration modes the INS error states, together with any navigation state (position, velocity, attitude) and other unknown parameters of interest, are estimated using GPS/GNSS measurements. In this study, the analysis has been carried out using the tightly coupled GPS/SDINS integration. In addition, it has been demonstrated that vehicle dynamics affect the Kalman filter initialization time, especially for the heading component.