Simulations investigating curved departure and arrival procedures using GNSS based vertical guidance

Building further on previous PBN to precision final approach transition work such as Radius-to Fix (RF) in extended terminal area procedures EUROCONTROL in collaboration with the Technical University of Berlin (TUB) and under the SESAR ¹¹Single European Sky ATM Research 2020 work programme conducted an extensive flight simulation series. It complements previous studies by addressing the use of RF leg in high altitudes and during the departure phase of flight. In addition, a concept of using GNSS altitude for vertical navigation during curved transitions to final approach was researched. The study was performed via a set of flight simulations using professional flight simulators of various aircraft types (Airbus A340-300, Boeing 777-200, Boeing 737-300, Embraer 190, Bombardier CS100 and De Havilland Bombardier DHC-8-Q400). The tracking of the procedures containing RF legs at all altitudes was excellent in all evaluated aircraft types. Data analysis has shown that at the higher altitudes, the aircraft could reach the start of the RF at various altitudes, thus the design of the procedure should take into account the most conservative aircraft ground speed. Also, during departure phase, the RF leg was tracked with good precision by all aircraft types tested and for various take-off weights. Nevertheless, recorded data showed that individual aircraft performance had a great influence on the altitude the aircraft reached at the start of the turn, causing some aircraft to start turning well below the minimum altitudes that are applied in current procedure design criteria. Analysis of Required Navigation Performance (RNP) transition to Instrument Landing System (ILS), commonly abbreviated `RNP transition to ILS' with additional transition from barometric to geometric altitude using GNSS in the initial and intermediate approach phases has been evaluated. It enables smooth continuous descents and final approach glide path intercepts without the need for a straight intermediate segment between localiser and glide path intercept. The flight deck implementation of geometric altitude in the terminal area still requires some considerations. On the other hand, the use of geometric altitude will require a clear operational concept for practical implementation in an Air Traffic Management (ATM) environment.