Radar Altimeter Aiding of GNSS for Precision Approach and Landing of RPA

For successful integration into the National Airspace System (NAS), Remotely Piloted Aircraft (RPA) need to have the capability to land automatically at a wide range of airports with varying infrastructure. Well-established systems such as the Instrument Landing System (ILS) are often not available at airports expected to be served by RPAs, and the Ground Based Augmentation System (GBAS) is currently only available at a limited number of public airports (two airports in the U.S. [1]). This paper examines the feasibility of an aircraft-based augmentation to Global Navigation Satellite Systems (GNSS) navigation that does not require ground-based equipment, for the purpose of enabling precision approach and landing for RPAs.