Exploiting Modern Aircraft Navigation Performance through Combining a SAAAR Approach with an LPV Final

Next generation air transportation system (NextGen) concepts of operation may require aircraft to fly planned trajectories in four dimensions - three spatial dimensions and time. A prototype 4D flight management capability is being developed by NASA to facilitate the development of these concepts. New trajectory generation functions extend todaypsilas flight management system (FMS) capabilities that meet a single required time of arrival (RTA) to trajectory solutions that comply with multiple RTA constraints. When a solution is not possible, a constraint management capability relaxes constraints to achieve a trajectory solution that meets the most important constraints as specified by candidate NextGen concepts. New flight guidance functions provide continuous guidance to the aircraftpsilas flight control system to enable it to fly specified 4D trajectories. Guidance options developed for research investigations include a moving time window with varying tolerances that are a function of proximity to imposed constraints, and guidance that recalculates the aircraftpsilas planned trajectory as a function of the estimation of current compliance. Compliance tolerances are related to required navigation performance (RNP) through the extension of existing RNP concepts for lateral containment. A conceptual temporal RNP implementation and prototype display symbology are proposed.

This pap er presents the development and preliminary results of a trajectory analysis and modeling environment developed in MATLAB and applied to the study of the effects of navigation performance on arrival timing accuracy . This work supports ongoing efforts at The Boeing Company to develop new air traffic management (ATM) concepts and procedures based on accurate navigation standards such as Required Navigation Performance (RNP) and Required Time of Arrival (RTA) . The arrival management concept studied involves th e use of advanced ground automation that perform s sequencing and spacing based on FMS paths rather than relying on controller tactical vectoring . These paths can be defined in three dimensions from prior to top of descent (TOD) to the meter fix and then to the runway , potentially including speed and altitude constraints when needed and would be communicated to the air crew via voice communication and executed to standards (e.g. RNP, RTA) by t he air navigation function embedded in the Flight Management Syste m (FMS). This concept is viewed as a transition step towards the US next generation air traffic system currently being studied by the Joint Planning and Development Office (JPDO).

The aviation industry’s paradigm shift toward Performance-based Navigation (PBN) demands navigation algorithms that rigorously satisfy Required Navigation Performance (RNP) standards. However, existing studies often isolate multi-sensor fusion from integrity monitoring, failing to address the holistic airworthiness requirements of modern civil avionics. This paper proposes an integrated navigation framework that bridges this gap by coupling a Federated Kalman Filter (FKF) for adaptive data fusion with a hierarchical Fault Detection, Isolation, and Reconfiguration (FDIR) mechanism. Specifically, the architecture employs a Normalized Innovation Squared (NIS) test for hard faults and a State Chi-square test for soft faults, ensuring robust operation against GNSS anomalies. Additionally, a covariance-based diagonalization method is introduced to precisely calculate Actual Navigation Performance (ANP) in real-time. The framework is validated via a high-fidelity simulation of the RNP Authorization Required (RNP AR) approach at Dalian Airport. Results demonstrate that the proposed algorithm maintains position accuracy within stringent thresholds, and ensures containment probability, providing a robust foundation for next-generation RNP-compliant avionics.

Some of the busiest airports in t he NAS set the pace for the entire system. These busy a irports experience frequent delays, cancellations and other in efficiencies, and many of these effects tend to propagate regionally or nationally. At many airports, opportunities exist to mitigate the se effects, by improving parallel runwa y operations, converging runway operations, adjacent airport operations, and single runway access. Through the application of low Required Navigation Performance ( RNP ) values and approach and missed -approach paths th at are not straight in and straight out, these opportunities for improvement are enabled. Because these RNP approach features apply to certain oper ators and not to others, their application is limited to those locations where aircraft capabilities exist an d where benefits can be realized. These procedures are being developed as Special Aircraft and Aircrew Authorization Required (SAAAR) as a core Operational Evolution Plan ( OEP ) activity. Our paper will describe the applications of RNP SAAAR at these busy airports, and at a handful of airports where safety/risk mitigation needs can be addressed as well. Our paper will describe a benefits -driven prioritization scheme for implementation of public RNP SAAAR procedures, with details on certain sites and projec ts. The analysis and modeling for this work was performed by MITRE/CAASD and coordinated through a designated Working Group chaired by Dr. Hassan Shahidi under the Performance -Based Operations Aviation Rulemaking Committee (PARC) .

This paper describes a Traffic Flow Management stochastic optimization model that exploits increased navigation performance. The model integrates Traffic Flow Management strategies and avionics capabilities for the Next Generation Air Transportation System. It generates Traffic Management Initiatives that are designed to improve National Airspace System performance and considers best-equipped best-served prioritization schemes. This work extends previous approaches by considering Required Navigation Performance levels in the Super-Dense Operations airspace with probabilistic weather scenarios to minimize ground and en route holding delays. The paper also presents results of simulation experiments in which the feasibility of the optimization model was evaluated using several scenarios for a Super-Dense Operations problem around Chicago, including varied demand levels, Required Navigation Performance equipage distributions, and weather scenarios. The results show that without improved navigation performance system delays may increase up to five times with the expected threefold demand growth. Simulations also showed that the majority of delays may be eliminated with improved Required Navigation Performance equipage and Traffic Flow Management algorithms properly exploiting increased navigation performance.

Required navigation performance authorization required (RNP AR) approach (APCH) procedures are a special form of approaches with vertical guidance (APVs) where stricter navigation system requirements in terms of accuracy, integrity and functionalities allow smaller obstacle clearance areas and the use of curved legs in all approach segments. That leads to very flexible approach design possibilities compared to other instrument approach procedures. This paper guides through the development and initial evaluation of an RNP AR approach on runway 15L at Isa Air Base in Bahrain. The establishment of instrument approaches on this runway has been complicated so far because the final approach would have led straight through the controlled traffic region (CTR) of an adjacent air base. We show that entering the CTR, which ends less than 3.3 NM before the runway threshold, can be avoided with an RNP AR approach by employing a curved leg in the final approach segment and the highest possible navigation accuracy of RNP 0.1—two unique features of RNP AR APCH. We then fly and test the developed procedure in an Airbus A320 full-flight simulator under the wind and weather conditions considered by the procedure design rules. The results show that the actual navigation and flight technical performance met the required one under all conditions without the bank angle and effective glide path limits being exceeded. An initial flight test with a Boeing B737-800 showed that the approach can also be flown with sufficient accuracy in practice.

The APALS system is a precision approach and landing system designed to enable low visibility landings at many more airports than now possible. Engineering development of the APALS system began October 1992 culminating in the pre- production Advanced Development Model (ADM) system currently undergoing flight testing. The paper focuses on the Cat III accuracy and integrity requirements defined by ICAO, Annex 10 and the required navigation performance (RNP) tunnel concept. The resulting ADM architecture developed to meet them is described. The primary measurement is made with the aircraft's weather radar and provides range and range rate information to the ADM necessary to update the precision navigation state vector. The system uses stored terrain map data as references for map matching with synthetic aperture radar with synthetic aperture radar maps. A description of the pre-production flight test program is included. Testing is being conducted at six different airports around the country demonstrating system performance in various environmental conditions (precipitation, heavy foliage, sparse terrain, over water and turbulence). ADM flight test results of 131 successful CAT II hand-flown approaches at ALbuquerque, NM and Richmond, VA are presented. Detailed statistical analysis of these results indicate that the APALS system meets the RNP for Cat III.

As part of the U.S. Federal Aviation Administration's NextGen implementation plan, the employment of area navigation (RNAV) and Required Navigation Performance (RNP) procedures is a key near to midterm initiative. RNAV and RNP allow for more optimal utilization of available airspace and enable more efficient, precise, and predictable routes. Over the last several years, researchers have identified significant quantitative benefits primarily related to aircraft operators, including reduction in miles flown, fuel consumed, and improvements in scheduling. However, metrics have not been developed to quantitatively assess the impacts that RNAV/RNP implementations have on air traffic controllers. This paper provides an approach to determine en route and terminal area voice communication benefits by utilizing communication event detection algorithms on historical audio and radar track data. The MITRE Corporation's Center for Advanced Aviation System Development (CAASD) leveraged Automatic Speech Recognition (ASR) and phoneme-based audio retrieval technologies - adapted to Air Traffic Control (ATC) phraseology - in order to automate the processing of controller to pilot audio data. The methodology and tools developed will allow one to process both audio and radar track data for the purposes of identifying voice communication benefits due to the implementation of RNAV/RNP procedures.

The role of inertial backup of GPS-based landing systems in the improvement of continuity is investigated. The purpose is to understand the relationship between the grade of inertial system and the system accuracy during various GPS discontinuity scenarios. GPS outages are considered at various locations on the approach. For systems that included pseudolites (PLs), outages are considered before entering the PL range of coverage (the "bubble") and after exiting the bubble. The inertial systems are assumed to be calibrated by GPS during the enroute portion of flight. Linear covariance analysis and Monte Carlo techniques are used to determine the navigation accuracy at the runway threshold to determine whether the system meets the various levels of Required Navigation Performance (RNP). It was found that in the event of a total loss of satellite GPS signals prior to bubble entrance, a navigation grade INS could be calibrated by 3 suitably placed PLs sufficiently accurately to provide an RNP that allowed the most stringent landing minimums (Category III). Other less drastic outage scenarios all indicated that substantial improvements in continuity can be achieved with inertial system augmentation. Except for GPS outages within 50 seconds of touchdown, navigation grade inertial systems were required for useful improvements. Conditions that allow tactical missile grade inertial systems for CAT III RNP for the case of a GPS outage within 50 seconds from touchdown are specified.

The use of the required navigation performance (RNP) procedure has been increasing for aircraft navigation, since it allows for better optimisation of the airspace, which is increasingly congested. The present work aims to investigate the application of the functional resonance analysis method (FRAM), combined with the quantitative analysis provided by the Bayesian belief network (BBN), to demonstrate the existing variability in functions that are part of the complex navigation system based on the RNP procedure, specifically when the aircraft approaches the airport (approach phase). As a result, it is possible to analyse the variability that occurs in the studied system and the BBN complemented the study by allowing a quantitative interpretation of the functions considered most important for the execution of an RNP approach procedure.

The Global Navigation Satellite System (GNSS) is strongly dependent on the choice of the satellite constellation. At the present time, the GNSS space segment is made by the following satellite constellations: GPS, GLONASS and a set of geostationary satellites. In a medium-long term future, a new GNSS could substitute the existing satellite navigation system, or, in any way, there will be an overlapping and an integration between the current system and the next one.Alenia Aerospazio, is studying, since 1990, the possibility to identify new navigation satellite constellations able to verify the Required Navigation Performance (RNP) for all users. Particular attention has been focused on airspace users, due to the fact that the accuracy requirements during the aircraft landing phases are very stringent, and the existing GPS system is not able to guarantee the desired RNP.In this paper a new satellite constellation with 75 satellites in Low Earth Orbit (LEO) at a common altitude of 2700 Km, and a common inclination of about 66°, has been identified. It is able to comply with the RNP (i.e. accuracy, availability, continuity, and integrity) up to CAT I landing.The transition phase between the co-existence of the current GNSS space segment and the evolving LEO constellation is discussed and analysed in this paper, outlining the advantages, with respect to the previous system, coming from the progressive implementation, in a step-wise fashion, of this LEO space segment, until its completion.KeywordsGlobal Navigation Satellite SystemGlobal Navigation Satellite SystemOrbital PlaneTime PercentageSatellite ConstellationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

The differences in performance of various manufacturers' Flight Management Systems (FMSs) and their associated Flight Management Computers (FMCs) have the potential for significant operational impact on the air traffic control system and as such need to be examined on a recurring basis. Performance-based navigation (PBN) is a fundamental principle for aircraft operations that will facilitate the transition to future airspace systems. A critical element of PBN is the FMS's capability to fly a consistently repeatable and predictable flight path trajectory that will meet the expectations of air traffic control. FMS manufacturers build their systems in accordance with and for area navigation systems, Technical Standard Orders and Advisory Circulars. Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures and routes are published by the Federal Aviation Administration (FAA) according to criteria contained in FAA orders. It is anticipated that the resulting performance of the aircraft FMC will meet the procedure design requirements identified in the FAA criteria. Sometimes, due to the nearly independent development of procedure design criteria and aircraft performance standards, the paths of various aircraft on the same procedure do not coincide and therefore do not match the expectations of the procedure designer. These differences may result from any or all of the following: variations in FMC equipment installed on the aircraft; variations and errors in procedure coding in the FMC navigation database; variations in aircraft-to-FMC interface and associated aircraft performance capabilities; and variations in flight crew training and procedures. The hypothesis of this paper is that the FMCs built by avionics manufacturers and installed as the core of the FMC/FMS combinations in various airframe platforms perform differently and we will attempt to quantify those differences. This paper focuses on FMC performance when flying Standard Instrument Departures (SIDs) and their associated waypoints and leg types (path terminators) and combinations as described in. Public instrument procedures flown using RNAV equipment are used as the baseline for measuring the performance variations. Controlled field observations trials were made using twelve FMS test benches and three simulators at seven major FMC manufacturers and two airlines. Analysis of data from the trials confirms differences and the details are presented. The intent of this report is to contribute technical data as a foundation for the acceptance of required navigation performance (RNP) departures.

Next generation flight management systems require the compliance of temporal and spatial constraints on navigation performance. The problem of generating fuel-efficient trajectories for aircrafts that comply with the required navigation performance is approached from an optimal control framework. By deriving the necessary conditions for optimality, nominal optimal control signals can be generated in a computationally efficient manner. These control signals can be used to generate nominal trajectories for an aircraft model. Using the nominal control and nominal trajectory, a feedforward-feedback control scheme can be implemented to robustify the system's response in the presence of uncertainty and disturbances to still achieve the required navigation performance. The feasibility of the approach is demonstrated through simulation and Monte Carlo runs.

Design, implementation and flight testing of advanced RNP to SBAS LPV approaches in Germany

According to Sheridan and Verplank's classification of levels of automation, taxiing on an airport still has a very low automation level. Key element for increased automation in taxi guidance is a precise and reliable navigation capability. As a Ground Based Augmentation System (GBAS) can fulfill the stringent requirements for a precision approach, it can play an important role in providing the required navigation performance during taxiing as well. This paper will explain the use of GBAS for taxi guidance. It presents, how the required navigation performance for automatic taxiing can be provided using GBAS. Besides the highly precision position service provided via Differential GPS, the Terminal Area Path (TAP) messages will be used to provide the aircraft with accurate and reliable information about the taxi route. Taxi trials with DLR's A320 research aircraft ATRA (Advanced Technology Research Aircraft) and the GBAS ground station at airport Braunschweig-Wolfsburg (EDVE) showed that over the whole maneuvering area the received VHF signal level was adequate for transmitting such a “Ground-TAP”. These tests were performed with an antenna on the aircraft located at a height of 8ft, which is lower than the actual required coverage minimum of 12ft defined in ICAO Annex 10. Together with a redefined voice communication structure and a list of predefined routes the use of GBAS for taxi routing functionalities of an Advanced Surface Movement Guidance & Control System (A-SMGCS) is feasible. Due to the independency from an on-board database the combination of such a message broadcast and the GNSS based positioning can be the key enabler for a future auto taxiing functionality.