A combined altitude display apparatus for generating a combined altitude value is provided. The apparatus comprises a first altitude input interface, wherein the first altitude input interface receives a first altitude value; a second altitude input interface, wherein the second altitude input interface receives a second altitude value, wherein the second altitude value indicated by the second altitude input interface has a cyclical range; an altitude output interface, wherein the altitude output interface outputs a third altitude value; and a data fusion component coupled to the first altitude input interface and the second altitude input interface and configured to calculate the third altitude value based on the first altitude value and the second altitude value.