Present novel and non-trivial systems and methods for validating navigation data are disclosed. A processor receives navigation data from an external source such as a global positioning system (“GPS”); receives navigation data from a second source comprised of multiple sources; determines the validity of the GPS navigation data; and alerts the pilot if validity of the data falls outside a limit. In an embodiment related to lateral information (i.e., geographic position) data, the second navigation data is comprised of both GPS data and data provided from an internal source. In an embodiment related to altitude information data, the second navigation data is comprised of both GPS data and data provided by multiple internal sources.