I don't think this warning can be resolved here, as it is dependent on Android. That means that if a fix is necessary it will have to come from the source, i.e. the Android GCS. @peabody124 Does AGCS use getAltitude() or does it parse the NMEA stream? If using getAltitude(), it might make sense to parse the $GPGGA stream once at startup in order to infer if altitude is referenced to the ellipsoid or the geoid.