Path Steering Error & Turn Analysis of Multiple Aircraft in the Current ECAC Fleet

EUROCONTROL, the Technical University of Berlin and Lufthansa Aviation Training conducted a series of flight tests in the frame of Horizon 2020 SESAR PJ.14-1.1 “CNS Environment Evolution” using CS-FSTD Level D certified Full Motion Flight Simulators to analyse the Path Steering Error (PSE) and budget allocation for this error in the computation of the navigation Total System Error. Additionally, the performance and behavior of aircraft while executing turns in the trajectory was analysed. To make the analysis as broad as possible with an optimal coverage of investigated navigation and flight guidance-systems used in ECAC, the tests were performed in a range of different aircraft types including Airbus A319, Airbus A340-300, Airbus A220-300, Boeing 737-300, Boeing 777-200, Boeing 747-400, Embraer E190, De Havilland Canada DHC-8-Q400, Embraer E145 and Bombardier CRJ-200. In each aircraft, two different trajectories were flown under known operating conditions using both the autopilot and manual flight using Flight Director. Recorded data was used to deduct the resulting Path Steering Error and turn performance indicators (bank angle and turn radius). The generated data provides valuable information about the actual navigation performance of modern aircraft, in contrast to the assumed PSE values and turn performance requirements in the current standards (MOPS DO-283B & MASPS DO-236C). A lower assumed PSE could allow using less accurate navigation sensors for certain PBN applications while maintaining the same overall TSE. For example, if the adjusted PSE is low enough, ground based DME-DME sensor combination could be used to serve Performance Based Navigation (PBN) operations with a Required Navigation Performance of 0.3NM. The demonstrated PSE was in the order of magnitude of 0.1NM for both the trajectories flown using autopilot and manual flight with Flight Director, which is a reduction compared to the values from DO-283B. A wide spread of tracks was observed in the turns, which were all executed as “fly-by” turns. Depending on the track change and aircraft type, applied bank angles ranged from 5 to 30 degrees, with resulting turn radii ranging from 38 to 1 NM. All the tracks were within the fly-by transition area defined in DO-236C. The huge spread of tracks in the turns makes revision of the conservative definitions of the fly-by transition area challenging but not impossible.