Showing papers on "Required navigation performance published in 2003"

Map-matching in complex urban road networks

Abstract: Global Navigation Satellite Systems (GNSS) such as GPS and digital road maps can be used for land vehicle navigation systems. However, GPS requires a level of augmentation with other navigation sensors and systems such as Dead Reckoning (DR) devices, in order to achieve the required navigation performance (RNP) in some areas such as urban canyons, streets with dense tree cover, and tunnels. One of the common solutions is to integrate GPS with DR by employing a Kalman Filter (Zhao et al., 2003). The integrated navigation systems usually rely on various types of sensors. Even with very good sensor calibration and sensor fusion technologies, inaccuracies in the positioning sensors are often inevitable. There are also errors associated with spatial road network data. This paper develops an improved probabilistic Map Matching (MM) algorithm to reconcile inaccurate locational data with inaccurate digital road network data. The basic characteristics of the algorithm take into account the error sources associated with the positioning sensors, the historical trajectory of the vehicle, topological information on the road network (e.g., connectivity and orientation of links), and the heading and speed information of the vehicle. This then enables a precise identification of the correct link on which the vehicle is travelling. An optimal estimation technique to determine the vehicle position on the link has also been developed and is described. Positioning data was obtained from a comprehensive field test carried out in Central London. The algorithm was tested on a complex urban road network with a high resolution digital road map. The performance of the algorithm was found to be very good for different traffic maneuvers and a significant improvement over using just an integrated GPS/DR solution.

An Extended Kalman Filter Algorithm for Integrating GPS and Low Cost Dead Reckoning System Data for Vehicle Performance and Emissions Monitoring

Abstract: This paper describes the features of an extended Kalman filter algorithm designed to support the navigational function of a real-time vehicle performance and emissions monitoring system currently under development. The Kalman filter is used to process global positioning system (GPS) data enhanced with dead reckoning (DR) in an integrated mode, to provide continuous positioning in built-up areas. The dynamic model and filter algorithms are discussed in detail, followed by the findings based on computer simulations and a limited field trial carried out in the Greater London area. The results demonstrate that use of the extended Kalman filter algorithm enables the integrated system employing GPS and low cost DR devices to meet the required navigation performance of the device under development.

Synthetic Vision Enhances Situation Awareness and RNP Capabilities for Terrain-Challenged Approaches

Abstract: The Synthetic Vision Systems (SVS) Project of Aviation Safety Program is striving to eliminate poor visibility as a causal factor in aircraft accidents as well as enhance operational capabilities of all aircraft through the display of computer generated imagery derived from an onboard database of terrain, obstacle, and airport information. To achieve these objectives, NASA 757 flight test research was conducted at the Eagle-Vail, Colorado airport to evaluate three SVS display types (Head-Up Display, Head-Down Size A, Head-Down Size X) and two terrain texture methods (photo-realistic, generic) in comparison to the simulated Baseline Boeing-757 Electronic Attitude Direction Indicator and Navigation / Terrain Awareness and Warning System displays. These independent variables were evaluated for situation awareness, path error, and workload while making approaches to Runway 25 and 07 and during simulated engine-out Cottonwood 2 and KREMM departures. The results of the experiment showed significantly improved situation awareness, performance, and workload for SVS concepts compared to the Baseline displays and confirmed the retrofit capability of the Head-Up Display and Size A SVS concepts. The research also demonstrated that the pathway and pursuit guidance used within the SVS concepts achieved required navigation performance (RNP) criteria.

Integration of GPS and dead reckoning for real-time vehicle performance and emissions monitoring

Abstract: Transport-related environmental problems continue to constitute a major challenge to policy makers at all levels. A key feature of these problems is that they arise from the interaction of human behavioral systems and physical systems. Thus, to improve our understanding of environmental and health problems associated with vehicle emissions it is necessary to combine data on both travel and traffic behavior with environmental data linked to the corresponding spatial and temporal variables. There are currently no such databases available. A new low-cost real-time device is currently under development utilizing the latest developments in environmental monitoring, navigation, communications, data mining and warehousing to capture spatio-temporally referenced data on vehicle and driver performance and the level of emissions and concentrations. Because of the need to acquire data in all environments, there are potential limitations in using a global satellite navigation system such as GPS to determine the spatial and temporal data in built-up areas. Therefore, an augmentation strategy involving differential GPS and new low-cost dead reckoning sensors utilizing micro-electro-mechanical systems technology has been explored. This paper presents a high-level description of the real-time vehicle performance and emissions monitoring system, and details the results of a study carried out to characterize the performance of stand-alone and augmented GPS, and assess whether the required navigation performance is achievable. The study characterized the performance of different types of stand-alone GPS receivers and GPS augmented with differential infrastructure and low-cost dead reckoning sensors. The performance indicators used were satellite visibility, coverage, accuracy and integrity. The results highlight the weaknesses and differences in performance, depending on the type of GPS receiver used and shows that, unlike GPS alone, an integrated system employing GPS and low-cost dead reckoning sensors is capable of meeting the required navigation performance in built-up areas. Furthermore, no significant difference in accuracy between stand-alone GPS and differential GPS has been seen.

Terminal area operations with enhanced and synthetic vision: experience in the Boeing technology demonstrator

Abstract: Several emerging technologies were recently demonstrated in a Boeing 737-900 as part of Boeing's Technology Demonstrator program. Among these technologies were two enhanced vision systems and a synthetic vision system, including synthetic displays to support surface operations. This project gained operational experience with enhanced and synthetic vision systems operating in a context that included Required Navigation Performance (RNP) terminal area operations, Global Navigation Satellite System (GNSS) approach and landing, and Integrated Area Navigation (IAN). The technologies were demonstrated to a broad mix of constituents involved in research, regulation, and acquisition in the transport category environment. This paper describes the systems demonstrated, the context in which they were used, and perceived benefits of integrating them in an operational environment. Lessons learned in the implementation of these technologies throughout the program are described and subjective data from participants are summarized.

Use of Military GPS in a Civil Environment

Abstract: The United States Department of Defense (DOD) has a significant investment in the development of GPS technology. The commercial world has expanded both the scope and role of GPS technology and, using Standard Positioning Service (SPS) or Coarse Acquisition (C/A) receivers, has developed certification standards for use as navigation sensors by aircraft flying in commercial airspace. Through the use of Precise Positioning Service (PPS) capability, or P(Y) code receivers, DOD GPS receivers can maintain high levels of accuracy and integrity even in the presence of jamming. Use of PPS GPS, blended with inertial or terrain following sensors, provides extraordinary navigation capability. Certification agencies have rigid certification standards that must be met order to fly in commercial airspace. These standards are a function of the navigation sensor being used in the aircraft. With details associated with the implementation of PPS equipped GPS units being classified, getting certification of aircraft that plan to use PPS GPS receivers in commercial airspace can be difficult. As a result of the congressional mandate to install GPS on all military aircraft by the year 2000, a large number of military aircraft have highly accurate multi-sensor navigation systems that use PPS GPS receivers. The military sensors and integration techniques are often complex and tailored for specific military missions, such as low level flight, terrain following, weapon delivery, etc. As a result, the military users have a large investment in their existing integrated navigation function that must be retained to meet their mission requirements. This paper describes a patented means by which a navigation system can utilize the precise positioning information from a military navigation function utilizing sensors, such as a PPS GPS compliant receiver, in commercial airspace and meet all civil certification requirements. This is accomplished by using an approved civil navigation sensor as a monitor while enabling use of a PPS GPS military solution as the primary navigation source. This paper specifically addresses using a blended INS/GPS solution, typically from an Embedded GPS/INS (EGI) sensor, as the primary navigation source and using a TSO certified DO-229A compliant GPS receiver as a monitor in a configuration that meets Required Navigation Performance (RNP) requirements as defined by RTCA/DO-236, Minimum Aviation System Performance Standards: Required Navigation Performance for Area Navigation. However, this concept can be extended to other sensor configurations to increase the integrity and continuity of the overall navigation system that will be needed by systems that must meet RTCA/DO-236 RNP requirements.

Terminal RNAV: analyses of Las Vegas McCarran International Airport terminal RNAV operations

Abstract: Area navigation (RNAV) allows a cockpit-based pre-planned traversal of airspace with automatic, precise following of lateral, vertical and speed profiles. With appropriate coordination, air traffic control (ATC) and pilot voice communications are reduced because the need for altitude, heading, or speed directives is reduced. Use of RNAV in the terminal area promises benefits that include lower radio frequency congestion, greater predictability of flight path and flying time, reduced fuel burn, and increased situational awareness. The Federal Aviation Administration (FAA) has tasked The MITRE Corporation's Center for Advanced Aviation System Development (CAASD) with assessing the impact of terminal RNAV at major airports in the US. This paper presents three analyses related to terminal RNAV performance and benefits at the Las Vegas McCarran International Airport (LAS) terminal area. We analyzed route conformance, predictability given good conformance, and performed human-in-the-loop simulations.

CNS/ATM for tactical military aircraft

Abstract: Military aircrews are beginning to experience the benefits of having quality global positioning system (GPS) navigation information available in the cockpit to support their tactical missions. However, another big improvement in situational awareness is the new capabilities known as communications, navigation, surveillance/ air traffic management (CNS/ATM). If tactical military are to operate within this new performance based airspace, they require operational RNP RNAV, Mode S, and 1090ES ADS-B functionality. To achieve these functionalities, dual use avionics and integrations must be found to capture civil functionality with military equipment. The bottom line is that tactical military achieves the required functionality or they can expect delays, rerouting, and some airspace exclusions. This paper describes one way to get RNP RNAV, Mode S, and 1090ES ADS-B capability in tactical military aircraft.

Flight Evaluation of GPS Aided Inertial Navigation Avionics with MSAS Augmentation (MSAS-GAIA)

Abstract: MSAS-GAIA is a next-generation aircraft on-board navigation system that integrates GPS with INS (Inertial Navigation System) and can utilize both wide- and local-area augmentation systems for GPS, in particular the MSAS augmentation system that will broadcast correction signals from the MTSAT satellite. A flight experiment was carried out to evaluate the performance of the MSAS-GAIA system. Because MTSAT is not yet on orbit, MSAS messages were transmitted to the experiment aircraft via a landline and local radio link. The system demonstrated good accuracy, with a 95% navigation error of 1.8m horizontal and 2.2m vertical during flights totaling eight hours. Error due to ionospheric delay and range error due to clock and satellite position errors were properly corrected using the MSAS messages. Integration with INS gave stable protection levels even during temporary loss of GPS signals, and 100% availability meeting APV-I required navigation performance was achieved. The smooth switching from satellite- to ground-based augmentation (MSAS to CDGPS/INS) was also successfully demonstrated.

Flight crew and aircraft performance during RNAV approaches: Studying the effectc of throwing new technology at an old problem

Abstract: Non-precision approaches (without vertical guidance) are known to expose aircraft to greater risk of CFIT (controlled flight into terrain). One solution consists of RNAV (area navigation) approaches with a computer-generated lateral and vertical path, which use the aircraft's flight management computer to fly an approach without any conventional ground-based radio facilities. We studied 22 pilots who flew 66 real RNAV approaches. Of special interest to us were the human factors and safety implications of using this new technology for an old problem. The high level of automation used for RNAV approaches brings with it a new potential for automation surprise (e.g. unexpected level-offs at go-around altitude) and extra monitoring requirements, especially for the pilot-not-flying. There is also an effect of low temperature that makes for shallower approaches as compared to ILS (instrument landing system). Pilot acceptance of RNAV approaches as measured in this study is high, and perceived mental workload for both pilot flying and pilot not-flying is low. This can be explained in large part by the shift from double-checking height against distance in traditional non-precision approaches, to pattern matching (aircraft symbol/reference) during RNAV approaches.

Modern rnav procedure design capabilities

Abstract: The demand for safe and useful procedures is increasing in the National Airspace Sy stem (NAS) to meet the needs of airlines and Air Traffic (AT) service providers. Area navigation (RNAV) and Required Navigational Performance (RNP) capabilities within the U.S. air carrier fleet continue to increase as airlines retire older aircraft and r eplace them with new more capable ones . Utilization of these avionics capabilities to execute new procedures is essential for more efficient use of airspace and as an enabler of op erational benefits . During the past three years , there has been a collabor ative effort by the Federal Aviation Administration (FAA), airli nes, and industry to develop new procedures for the terminal area. As part of this effort, The MITRE Corporation's Center for Advanced Aviation System Development (CAASD) worked with stakehol ders to capture the process for the design and development of procedures . Lessons learned have been incorporate d as more FAA facilities have used the process . The process has gained wider acceptance am ong stakeholders and has become the preferred guideli nes for procedure development with the primary benefits of fewer mistakes, less rework, and reduced time for implementation. Tools and automation , when strategically incorporated as part of the process, are a key method for workload reduction, elimination of paper, and elimination of inter -organizational stovepipes. This paper discusses a collaborative RNAV procedure tool developed by CAASD for the FAA and industry called Terminal Area Route Generation, Evaluation, and Traffic Simulati on (TARGETS) . The TARGETS application combines the science , engineering , and best business practices needed for procedure design. The functionality of TARGETS include s a geographic information system (GIS) tailored to procedure design, flyability assessment, protected airs pace surface generation, obstacle assessment, noise assessment, seamless data exchange with centralized databases and other applications , and simulation of t he operational environment. This paper discusses the role of each of these capabilities and relate d technical issues within the context of RNAV procedure development.

Performance Verification of GBAS through ILS Inspection Procedure

Abstract: There have been many researches to guarantee the required navigation performance of the CNS/ATM sub-systems (GBAS, SBAS, etc) mainly in the accuracy or integrity aspect However, it is also important the study about the interoperability and natural transition between the old and new nav-aids because of the very different features of them Therefore, we focused on the verification of the performance of the new systems, especially GBAS, through the comparison with the conventional aircraft landing guidance system such as ILS For the verification, we developed the GBAS system and conducted the ground tests, flight tests, and integrity monitoring tests Additionally, in the analysis of the test data, we compared the GBAS navigation solutions with the data which are collected from the ILS inspection device - theodolite From the analysis, we concluded that the developed GBAS system satisfied the Precision Approach Category I requirements in the aspect of accuracy, and had the consistency with the conventional aircraft precision approach guidance system

Loran Fault Trees for Required Navigation Performance 0.3

Abstract: Long Range Navigation or Loran is an attractive candidate for providing redundant services for GPS because of its complementary RNAV, stratum 1 timing, and data channel capabilities. However, for Loran to be accepted as a redundant navigation system for aviation, it must meet the accuracy, availability, integrity, and continuity standards for Required Navigation Performance 0.3 (RNP 0.3). The Loran Integrity Performance Panel (LORIPP), a core team of experts, has been chartered to assess Loran’s potential to meet the RNP 0.3 performance. Proof that the system meets RNP 0.3 requirements involves demonstrating that all system threats are accounted. The LORIPP is developing a comprehensive hazard list and fault trees for requirements such as integrity and continuity for Loran. The hazard list enumerates the noteworthy faults that can cause integrity, continuity, availability or accuracy concerns. The fault tree allocates the acceptable error probabilities for each fault with regard to the requirement. For example, the integrity fault tree list shows all faults that can cause an integrity failure or Hazardously Misleading Information (HMI) and the probability that the fault will cause the failure. The probability allocations are selected based on what is known, what can be proven or what is required to meet overall the system requirement. In the case of integrity, the requirement is that the probability of HMI be 10 per hour or less. The paper details the Loran integrity and continuity fault tree that is being designed and developed by the LORIPP. The key elements of the design such as the division of faults and the fault allocations are explored. The paper details the decisions made in the design of the fault trees and how the design aids requirements analysis and book keeping. The anticipated result of the Loran fault tree analysis is to prove that Loran can meet RNP 0.3 integrity and continuity requirements. This enables Loran to provide cost effective redundant aircraft navigation services for GPS.