Systems and methods for vehicle attitude determination are provided. In one embodiment, a method for vehicle orientation detection comprises: generating differenced carrier phase measurements based on measurements from an on-board GNSS Receiver System; receiving attitude aiding measurements and a baseline length from on-board aiding sources; calculating float ambiguity values with associated covariance values as a function of the differenced carrier phase measurements, attitude aiding measurements and baseline length; calculating a set of integer candidate arrays from the float ambiguity values, wherein the integer candidate arrays are calculated from dis-similar ambiguity estimation algorithms; selecting a first integer candidate array as resolved integer values as a function of residuals calculated from the differenced carrier phase measurements and the attitude aiding measurements and the baseline length and further based on comparing the plurality of residuals to a plurality of thresholds; and outputting the resolved integer values to an attitude and heading calculator.