Abstract: A self-contained, strapped down guidance system combining all axes, all attitude navigation having two wide angle, two-degree-of-freedom gyros which provide attitude angle and angular rate signals along three axes. Accelerometer means provide signals representative of the acceleration along three orthogonally displaced independent axes. A first transformation matrix connected to the attitude angle output of the gyros and to the accelerometers transforms the gyro and accelerometer signals from body coordinates to gyro coordinates. A second transformation matrix connected to the output of the gyros, transforms the gyro coordinates into navigation coordinates. In order to perform navigational computations, computing means compute a transformation from gyro momentum vector (referenced to coordinate frame) to a navigational coordinate frame such as a locally vertical frame wherein the Z axis is always along the local vertical direction.