Required navigation performance

About: Required navigation performance is a research topic. Over the lifetime, 343 publications have been published within this topic receiving 3477 citations. The topic is also known as: RNP.

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

Abstract: 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.

Midair collision risk when executing an incorrect approach during established on required navigation performance operations

Abstract: Providing improved efficiency in the terminal environment around high-capacity airports, Established on RNP leverages Required Navigation Performance technology to safely allow reduced aircraft-to-aircraft separation during curved simultaneous approaches. As one element in a comprehensive safety analysis, this paper describes the methodology and results used to estimate the mid-air collision risk when at least one aircraft leaves the intended approach path by inadvertently selecting an unintended flight procedure. The analysis considers three possible cases where an aircraft could be put at risk of collision during such an event: one where the trailing aircraft flying to the intended runway may be put at risk; a second where an aircraft flying to the incorrectly selected runway is put at risk; and, a third case, which only occurs when more than three parallel runways are available, where an aircraft flying to a runway between the intended runway and the incorrectly selected runway is put at risk of collision. The analysis concludes that all three cases could pose significant risk if not appropriately mitigated with controller monitoring and procedure design, but the third case is the most severe.

Performance Comparison Of A320 And 737ng Regarding The Vertical And And Speed Pro-Files In Advanced RNP To XLS Arrivals

Abstract: We report on the performance comparison between an Airbus A320 and a Boeing 737NG in vertical path following and speed profile during novel advanced required navigation performance (RNP) procedures which contain a fixed radius turn that delivers the aircraft onto a short ILS precision final. The approaches were flown automatically with guidance and automatic thrust as computed by the flight management system. Main areas of interest of the flight trials were the performance of the vertical path following during the RNP part of the procedure as well as maintaining an optimized speed profile during the continuous descent approaches. Within the PBN concept, it is possible to incorporate turns with a precise ground track into departure, en-route, arrival and approach procedures called fixed radius transitions or radius-to-fix. They offer the advantage of repeatable ground tracks during the turn and thus more freedom for the procedure designer when route planning in dense traffic, high terrain or obstacle rich environments. Additionally, ARINC 424 allows to specify altitude constraints at waypoints and vertical path angles for each RNP segment terminating at such a waypoint. The vertical path angle feature is currently largely unused and unexplored, except for the final approach segment of an RNP approach. These new options, when properly exercised, would allow any aircraft to benefit from better fuel efficiency during a continuous descent approach and a potentially reduced obstacle clearance due to the fixed vertical RNP profile and RF tracks. Ground tracks are repeatable and could be used for better noise abatement - besides their main purpose, obstruction clearance along the aircraft's path. In this study, we investigated the use of the ARINC424 coding options “vertical path angle” and “altitude constraints” at path terminators Track-to-Fix and Radius-to-Fix onto the performance of the speed profile for arrival time optimization and the vertical path following. Moreover, we study the influence of splitting the procedure into a standardt Terminal arrival route (STAR) and instrument approach procedure (IAP) components of varying lengths as shown in the Figure 1 below. The procedure designed for this experiment delivers the aircraft onto the instrument landing system of Braunschweig-Wolfsburg airport’s ILS runway 26. The glide path intercept point or final approach point (FAP) is located 1500ft above aerodrome level. The approach has 5 initial approach fixes (IAF) located 3,4,5,6 and 7 miles uptrack of the FAP. Additionally, 5 separate STARs were coded, all commence at the same point in the terminal area at an altitude of 4000ft MSL and ending at the respective IAF. The ground track for all 4 procedures is identical, only the transition from STAR to IAP is shifted. The descent angle from the beginning of the STAR until the FAP of the approach was designed and coded with 1° downwards. The idea is to test, where an automatic thrust reduction takes place in order to decelerate the aircraft as late as possible. We compare the performance between the two most commonly used passenger transport aircraft, the Airbus A320 and the Boeing 737NG. For the trials, we used DLR's own Advanced Technology Research Aircraft (ATRA), an Airbus A320 MSN659 with flight test instrumentation and a Thales flight management system (FMS) 2 as well as a Boeing 737-800 Simulator located at Lufthansa Flight Training in Berlin. The approaches were entirely flown using the auto flight guidance in managed mode and with automatic thrust activated. Results show that the 737 delivered the same performance at all 5 different coding options following the vertical and lateral path within the prescribed lateral and vertical required navigation performance. On the other hand, the A320 thrust reduction depended greatly on the point at which the IAF was located. The Airbus began to reduce thrust two miles before each the IAF which leaves insufficient time to decelerate in case of three miles track distance between IAF and FAP. While the B737 demonstrated the same behavior in vertical path following at all times, the A320s vertical path following depended on the energy state of the aircraft. In the “hot and high” case with 3 miles track between IAF and FAP, the vertical path was not maintained within the required corridor.

Integration of an ARAIM algorithm in the development of an instrument approach procedure and for pre-flight operational briefing

Abstract: Advanced Receiver Autonomous Integrity Monitoring (ARAIM) offers the opportunity to enable Global Navigation Satellite System (GNSS) receivers to serve as a primary means of navigation, worldwide, for precision approach down to Localizer Performance with Vertical guidance (LPV-200) operation. Previous produced works analysed the performance of this new technique, clearly showing the potential of ARAIM architectures to provide the Required Navigation Performance (RNP) for LPV 200. However, almost all of the studies were performed with respect to fixed points on a grid on the Earth’s surface, with full view of the sky, evaluating ARAIM performance from a geometrical point of view and using nominal performance in simulated scenarios lasting several days. In our previous work we presented the ARAIM performance in simulated operational configurations. Attitude changes from manoeuvers, obscuration by the aircraft body and shadowing from the surrounding environment could all affect the incoming signal from the GNSS constellations, leading to configurations that could adversely affect the real performance. In this paper, we continue the previous work. The new proposed algorithm integrates ARAIM performance prediction capability, considering the attitude and terrain shadowing effects, in two different scenarios: In the design of instrument approach procedures. The algorithm could be used to improve the procedure of the development of new instrument approaches, reducing time, effort and costs. In the aircraft Flight Management Systems. The algorithm could support the pilots in the pre-flight briefing, highlighting possible integrity outage in advance and allowing them to select a different approach or making them aware of the need to utilise additional positioning systems. Increased awareness and better pre-flight planning could ultimately improve the safety of flights and contribute to the safe introduction of GNSS as a viable positioning method for instrument approach.