Military avionics navigation systems are constantly demanding for exploding system performance and minimizing system size. They require higher accuracy, reliability, and robustness against jamming. This drives the system-integrators towards a generation based upon satellite navigation (GPS) and inertial navigation system (INS). This paper presents the solution of GPS navigation equations operating in a stand-alone configuration in a general environment. On the other hand, the solution of INS equations operating in a stand-alone configuration in the same environment. And finally, the solution of integrated GPS/INS navigation system, which will provide improvements in navigation performance are presented.