Systems and methods for determining if an aircraft is approaching a atmospheric pressure at field elevation (QFE) airport and for alerting if any errors that might affect the production of an accurate altitude value. In an example method a global positioning system (GPS) altitude value is compared to a corrected barometric altitude, if an airport that the aircraft is proximate to (approaching) is a QFE airport. The field elevation of the proximate airport is added to the corrected barometric altitude to generate an adjusted barometric altitude, if the comparison between the GPS altitude and the corrected barometric altitude is greater than a predefined threshold. The adjusted barometric altitude is sent to relevant aircraft systems, such as an Enhanced Ground Proximity Warning System.