Abstract: A position determining voting system that uses Doppler information from an on-board weather radar to improve the system's accuracy and/or fault tolerance includes a comparison function and an error integration function. The comparison function is used to monitor the independent position sources for correct operation, comparing and identifying a position source that should not be used based on its relative error compared with the other position sources and their characteristics. The integration function provides corrections to relative position sources by integrating the data from multiple absolute position sources when they are mutually consistent.