For years Inertial Labs has produced high accuracy Inertial Navigation Systems (INS) at the world’s best price-performance ratio. An INS estimates the position, attitude, and velocity using the gyroscopes and accelerometers contained inside an inertial measurement unit (IMU). Position accuracy can be greatly improved when the INS is aided by Global Navigation Satellite System (GNSS). However, GNSS is not always available. Customer requirements demand for better performance of an INS during GNSS outage. Outages can be caused by tunnels, urban canyons, roads under bridges, etc….