A method of aligning a gyro-compass comprising operating at least two
Kalman filters in a set of Kalman filters to generate an error correction
to at least a single navigation solution in a set of navigation solutions
in order to provide coarse alignment azimuth convergence. The method
further comprises selecting at least one selected Kalman filter from the
set of Kalman filters and at least one selected navigation solution from
the set of navigation solutions, and operating the at least one selected
Kalman filter and the at least one selected navigation solution to
provide fine alignment convergence to a correct azimuth. The selecting is
based at least in part on the generated error correction, each navigation
solution includes an azimuth different from the azimuth of each other
navigation solution and each navigation solution azimuth is separated by
no more than two times a small angle error assumption.