Combining Advanced-RNP with SBAS Guided Precision Terminal Area Paths and Final Approach Guidance

Abstract

Satellite based augmentation systems (SBAS) for Global Navigation Satellite Systems (GNSS) currently enable precise vertical and lateral guidance for aircraft during the final approach. The newly established advanced-Required Navigation Performance (RNP) concept allows all aircraft to follow repeata-ble ground tracks even during curved segments in the approach. This was previously only possible with special aircraft and air-crew authorization. Terminal Area Paths (TAPs) allow the path definition and vertical guidance during the arrival and initial through intermediate approach segment. Here, we report on the design and flight test results of advanced procedures that employ combinations of the three aforementioned possibilities. We in-clude TAPs, originally a concept from the Ground Based Aug-mentation System (GBAS), into the onboard FMS database in order to use them with an SBAS based navigation solution. The TAPs transition to a localizer performance with vertical guidance final approach segment, thus enabling vertically guided continu-ous descent approaches from cruise level at selectable descent angles down to 200ft. During the flight trials, an A320 research aircraft was able to follow the desired trajectory with vertical and lateral total system accuracy of less than 20 meters. Secondly, we show that combinations of advanced RNP with SBAS final approach segments can effectively decouple runways in dense traffic environments where these runways previously were pro-cedurally dependent. Sufficient obstacle clearance can also be achieved despite power lines with a height of ~300ft passing just south of the airport. While performing the flight trials, we rec-orded a lateral precision better than 44.5 m during a curved missed approach using automatic flight control in a Hawker 750XP business aircraft.