Abstract: In anticipation of a rapid increase in the number of civil Unmanned Aircraft System(UAS) operations, NASA is researching prototype technologies for a UAS Traffic Management (UTM) system that will investigate airspace integration requirements for enabling safe, efficient low-altitude operations. One aspect a UTM system must consider is the correlation between UAS operations (such as vehicles, operation areas and durations), UAS performance requirements, and the risk to people and property in the operational area. This paper investigates the potential application of the International Civil Aviation Organizations (ICAO) Required Navigation Performance (RNP) concept to relate operational risk with trajectory conformance requirements. The approach is to first define a method to quantify operational risk and then define the RNP level requirement as a function of the operational risk. Greater operational risk corresponds to more accurate RNP level, or smaller tolerable Total System Error (TSE). Data from 19 small UAS flights are used to develop and validate a formula that defines this relationship. An approach to assessing UAS-RNP conformance capability using vehicle modeling and wind field simulation is developed to investigate how this formula may be applied in a future UTM system. The results indicate the modeled vehicles flight path is robust to the simulated wind variation, and it can meet RNP level requirements calculated by the formula. The results also indicate how vehicle-modeling fidelity may be improved to adequately verify assessed RNP level.

Abstract: The invention provides a computer virtual environment simulation and check system for a performance based navigation (PBN) flight program, and belongs to the field of civil aviation navigation. The system comprises a data layer, a model layer, a display layer and an application layer, wherein the data layer is used for processing flight program data, topographic data and barrier data; the model layer provides a navigation system, a dynamic system and an enhanced ground proximity warning system of an airplane for virtual verification of the flight program; the display layer is used for providing two-dimensional display and three-dimensional visual systems for a user during virtual verification; and the application layer provides man-machine interaction and flight program verification applications for the user. The system realizes the verification of the PBN flight program in a virtual environment generated by a computer, is simple and convenient, shortens verification cycle, reduces costs and improves working efficiency; and a result can evaluate flight program design, guide actual flight verification and meet PBN flight program verification demands.

Abstract: A navigation system including a vehicle dynamic model (VDM) that serves as the main process model within a navigation filter is described. When used in an unmanned aerial vehicle (UAV), the navigation system may work in communication with inertial measurement units (IMUs) and environment dependent sensors such as GNSS receivers. Particularly, the navigation system is beneficial in the case of GNSS signal reception outages, where conventional IMU coasting drifts quickly. Yet, the navigation system may also be employed in other scenarios, for example during GNSS presence for improved positioning, velocity and attitude determination, or in combination with GNSS when no IMU is available by design or due to a failure. In the navigation system, a solution to VDM equations provides an estimate of position, velocity, and attitude, which can be updated within a navigation filter based on available observations, such as IMU data or GNSS measurements.

Abstract: Modern warships are often equipped with small airstrips that are dedicated to helicopters or other vertical take-off and landing (VTOL) units. Therefore, this type of vessels should have navigation systems that provide process automation of take-off and landing for these flying units. Currently, the Global Navigation Satellite Systems (GNSS) is used for this purpose. The accuracy of the positioning based on GNSS may prove to be insufficient during automatic landing approach of unmanned aerial vehicles. In the military operation area, GNSS signals may be jamming or spoofing. Additionally, it may be limiting visibility related to smoke screens or natural factors, e.g. fog. Thus, there is a need for a dedicated radio navigation systems. This paper presents a concept of the local navigation system (LNS) that based on the signal Doppler frequency (SDF) location method. LNS allows positioning of the landing VTOL with high precision. The accuracy of VTOL positioning in LNS is shown on the basis of two scenarios of simulation studies.

Abstract: The paper is aimed at the analysis of possibilities of the implementation of the hyperbolic TDOA (Time Difference Of Arrival) based system intended for aircraft navigation during the approach to landing phase of flight. For this purpose, conventional systems like ILS, MLS, GNSS, etc. are used today. Requirements on hyperbolic system were determined based on accuracy of actually utilized systems. The possibility to achieve these requirements was verified by simulation for LKPD Pardubice airport. The final section describes the configuration of the system together with proposed coded signals, which are starting point for initial real experiments.

Abstract: New Air Traffic Management (ATM) concepts aim at enabling an increase in air traffic while at the same time maintaining the same or a better level of safety. Key enablers for these new ATM concepts are evolving technologies which are successively included in aircraft guidance and control functions. Some components of theses evolving ideas were already introduced in the ATM environment– such as Required Navigation Performance (RNP) - or are in the process of being researched and tested such as Required Time of Arrival (RTA) or advanced RNP. Moreover, with the evolution of air to ground datalink communications, full four-dimensional trajectories could be negotiated between air traffic control and the aircraft and flown in free route airspace [0]. While research into datalink communications, the trajectory management process and conflict resolutiosn are actively being pursued by the ATM research community, so far no requirements for a continuous four dimensional airborne navigation performance have been investigated or specified. Four-dimensional navigation requirements would describe the minimum capability of the aircraft to adhere to the trajectory that was assigned by or negotiated with ATC in the cross-track, along track, vertical and temporal dimension. As such, they would define a 4D RNP concept evolving from the current cross-track RNP specifications [1]. Presently, RNP is a designator for an area navigation system for use within a performance based navigation concept. RNP also includes continuous monitoring of navigation performance and alerting of the pilot in case of failure [1]. Only lateral (or cross-track) RNP accuracy is indicated by a number following the letters RNP, (i.e. RNP 0.3 for 0.3 nm accuracy). In this case, accuracy relates to the Total System Error (TSE) which is a combination of the Flight Technical Error (FTE) and the Navigation Sensor Error (NSE), and designates the 95% uncertainty bounds. Vertical guidance during an RNP operation is accomplished using barometrical vertical navigation (Baro VNav). Limiting factors for vertical navigation are the barometric uncertainty of the altimeter and the human factor in determining the pressure value for the pilot to set in the airplane and no monitoring or position error estimation exists for such Baro VNav systems. In the work presented here, we derive requirements for the missing dimensions vertical, along track and time from high level ICAO prerequisites and presently applicable separation standards. In addition, we introduce new algorithms based on augmented GNSS that continuously monitor the system performance in those additional dimensions. A four dimensional RNP concept needs to be seen as an extension of the current RNP definitions and must include a required navigation performance for the vertical and the along track dimension as well as for time. The along-track or longitudinal component is tightly connected to the time component by means of speed and the RTA at each given waypoint. Thus, from a top-down point of view, it makes sense to define requirements jointly for the along-track / longitudinal component and time through the concept of required time of arrival and speed control. Vertical Required Navigation Performance (vRNP) could be specified as a separate component, since it is largely independent of the other dimensions. Vertical performance requirements are already formulated to some degree for legacy systems. Attachment A to Volume 2 of [1] describes the accuracy requirements of the altimeter system for Baro VNav approach operations. The ICAO documentation on Reduced Vertical Separation Minimums (RVSM) [2] specifies the integrity requirements for altitude in a high density enroute traffic environment. For the vertical RNP, we merge the existing requirements from both documents. Assuming a zero mean Gaussian distribution for the altitude error, a system with a standard deviation of 5.05 m can fulfill this requirement. The limiting factor is the accuracy required by [1], whilst [2] would allow a tail heavy distribution. It is notable that RVSM requires about the same error probability for a vertical error exceeding 90m which the PBN manual requires for an error exceeding 15m during instrument approach. In order to complete the requirement for vRNP, we suggest a monitoring and alerting function which warns the pilot in the case of malfunctions of the barometric altimeter. The monitor performance must also comply with the previously defined error curve. We show that an algorithm using a GNSS solution augmented by a regional augmentation system such as WAAS or EGNOS can be used for monitoring the barometric altitude. The suggested system is capable of monitoring altitude deviations in level flight and up to a certain descent or climb path angle. In the case of longitudinal and time navigation performance no such prerequisites as for vertical RNP exist. Same track separations considerations are largely based on collision risk models that are specifically tailored to a target airspace. Here, for along track RNP and the desired target level of safety given by ICAO, we define requirements for arrival at any point on a trajectory at a given time. Required arrival time accuracy at waypoints is be closely linked to a minimum along track separation requirement as well as separation requirements at merging points of trajectories. We found that the required along track accuracy depends largely on the number of aircraft on a specific route and their respective speed. Results show that, for example, in order to reach a target level of safety of 5x10^-9 with 10 aircraft per hour on a given route crossing a given point, an along track accuracy of 2875 m is needed. With a speed of 400 knots this is equivalent to a required temporal accuracy of 13.5 s assuming no uncertainty on the speed. Along –track position and velocity monitoring is already accomplished by the algorithm for receiver autonomous integrity monitoring (RAIM). The onboard clock needs to be synchronized to a common time base, preferably UTC as it is already used as common reference time for aviation. Since satellite navigation systems are time based, the navigation solution already incorporates clock synchronization with the GNSS time base accurately up to a few milliseconds. Therefore, if the flight management computer is synchronized with GPS time, a precise time reference is always assured, as long as a navigation solution is available. Regional augmentation systems can support the clock accuracy by detecting common system biases in the satellite navigation system that would otherwise map to the clock correction. For redundancy of the clock monitoring, we recommend that two independent systems are used to derive separate clock solutions. One form of cross checking can be a comparison of the UTC time derived from GPS with the UTC time derived from EGNOS or Galileo.

Abstract: Unmanned aerial vehicles (UAV's) have become smaller and less expensive making them accessible to businesses, law enforcement and the general public Businesses have proposed ways to use these aircraft for commercial purposes For unmanned aerial systems to be used on a large scale, an autonomous flight control system needs to be developed However under current and proposed FAA regulations, all UAV's must be piloted by people to fly in the national airspace In order for a system like this to be adopted it needs to minimize the amount of changes to the current air traffic control system to reduce costs and air traffic controller training A system design for this purpose is discussed in this paper

Abstract: Many new Performance Based Navigation (PBN) Instrument Flight Procedures (IFPs) are being developed as the United States transforms its airspace to improve safety and efficiency. Despite significant efforts to prepare for operational implementation of new IFPs, the process does not always go smoothly. The primary goal of this study was to understand what makes IFPs difficult from the perspective of line pilots. We spoke to 45 professional pilots in small groups. The pilots reviewed, briefed, and discussed six IFPs in an office setting. We extracted a comprehensive list of subjective complexity factors by observing pilot briefings and gathering pilot feedback. Then we organized the list into a framework that captures a variety of types of complexity. We define a subjective complexity factor as one that requires an extra mental or physical step by the pilot. IFP design parameters (e.g., the number of transitions and flight path constraints) are a main driver for subjective complexity for line pilots. Unusual IFP designs can result in novel chart depictions that are unfamiliar and more difficult to use. In turn, novel chart formats may have inconsistencies that increase subjective complexity. Participants also mentioned factors that are outside the control of IFP designers, such as weather, fatigue, and aircraft performance or equipment. We separate out these as operational complexity factors. The broad nature of the pilot interviews also provided insights into how pilots use charts today, in the context of the modern flight deck. A full report on the study is in preparation.

Abstract: The implementation of performance-based navigation allows advanced flight operations in areas without conventional navigation aids. Especially helicopter operations, which usually have been conducted under Visual Meteorological Conditions (VMC), may now operate more independently of the weather situation under Instrument Flight Rules (IFR). Nevertheless, at common helicopter IFR flight altitudes, icing conditions are a major threat. Therefore, helicopter operators have a signi¬ficant interest to fly at the lowest possible altitude. High navigation accuracy and reliability is imperative for such flight operations, this holds true especially in mountai¬nous areas. In the frame of the Swiss-wide implementation program to promote GNSS procedures and performance based navigation applications (CHIPS), a low-level flight net-work for helicopter operations is being implemented in Switzerland. The newly developed routes are still designed at relatively high altitudes and lowering them closer to the ground is definitively envisaged. For such operations, the RNP 0.3 navigation specification would however not suffice. A more ambitious performance would be in demand. The highest risk in low-level flight operations is the proximity to the terrain. Loss of navigation for instance due to an RF-interference event or even because of an insufficient satellite coverage may immediately lead to a hazardous situation. In order to analyze the performance of helicopter operations, 11 Agusta DaVinci helicopters have been equipped with a recording unit to obtain on-board GPS, EGNOS, FMS and flight plan information. As additional data recording measure, a geodetic receiver may be installed on-board the helicopter to record GPS and GLONASS dual-frequency data. These recordings allow the determination of the true flight path. Data is recorded in daily operations whenever possible. More than two dozens of flights have been analyzed so far. In addition, a dedicated high dynamic test routing has been developed using straight segments and RF legs featuring extremely narrow radii which are beyond the limitations of the current ICAO criteria. Furthermore, an approach procedure with RNP 0.1 performance including RF legs has been used. The resulting total system error usually remained below 0.02 NM. With few exceptions, all dedicated operations have been flown without issues. In summary, the investigation shows that a more ambi-tious RNP navigation accuracy requirement than 0.3 NM is feasible for advanced rotorcraft operations. Such performance-based navigation applications would allow safe flight operations at a lower flight altitude. For HEMS organizations, this would allow a significant increase of the efficiency and a more robust rescue service resulting in human life savings.

Abstract: NASA is participating in the International Committee on Global Navigation Satellite Systems (GNSS) (ICG)'s efforts towards demonstrating the benefits to the space user in the Space Service Volume (SSV) when a multi-GNSS solution space approach is utilized. The ICG Working Group: Enhancement of GNSS Performance, New Services and Capabilities has started a three phase analysis initiative as an outcome of recommendations at the ICG-10 meeting, in preparation for the ICG-11 meeting. The first phase of that increasing complexity and fidelity analysis initiative is based on a pure geometrically-derived access technique. The first phase of analysis has been completed, and the results are documented in this paper.

Abstract: Inertial sensors constitute an essential part in civil avionics systems. It has also been identified as a required system to meet the foreseen availability requirements in the context of Alternative Position Navigation and Timing (APNT). For example, DME/DME/Inertial (DDI) is currently considered for RNAV 1.0 operations. In this work, we look beyond DDI and investigate the possibility of an integrated inertial system with multiple APNT ranges. Thanks to our simulation framework, we evaluate in different scenarios the integration of inertial system with ranging sources using real DME locations. Based on the results, we finally analyze and comment on the limitations, implications and issues of using tactical grade instead of navigation grade inertial sensors.

Abstract: Systems and methods for predicting aircraft navigation performance are provided. In one embodiment, a method can include determining that one or more navigational aid measurements are not available to the aircraft. The method can include estimating a future actual navigation performance of the aircraft for a future point in the flight plan. The method can include determining a future required navigation performance associated with the future point in the flight plan. The method can include comparing the future actual navigation performance to the future required navigation performance to determine if the future actual navigation performance satisfies the future required navigation performance. The method can include providing, to an onboard system of the aircraft, information indicative of whether the future actual navigation performance satisfies the future required navigation performance.

Abstract: The Next Generation Air Transportation System (NextGen) refers to the federal programs (predominately airspace, air traffic, or avionics related) that are designed to modernize the National Airspace System (NAS). ACRP’s NextGen initiative aims to inform airport operators about some of these programs and how the enabling practices, data, and technologies resulting from them will affect airports and change how they operate. This volume, the first report in this series, provides comprehensive information to practitioners concerning all aspects of Performance-Based Navigation (PBN) and how implementation affects overall airport operations. This Resource Guide encompasses background information, description of effects on short- and long-term airport development, impacts on safety and performance measures, and other critical factors affecting future airport operations. In addition to providing guidance to users on available resources for additional assistance, this volume also includes lessons learned and best practices based on findings from case studies that examined the airport operator’s role in PBN implementation.

Abstract: The development of new GNSS constellations, and the modernization of existing ones, has increased the availability and the number of satellites-in-view, paving the way for new navigation algorithms and techniques. These offer the opportunity to improve the navigation performance while at the same time potentially reducing the support which has to be provided by Ground and Satellite Based Augmented Systems (GBAS and SBAS). These enhanced future capabilities can enable GNSS receivers to serve as a primary means of navigation, worldwide, and have provided the motivation for the Federal Aviation Administration (FAA) to form the GNSS Evolution Architecture Study (GEAS). This panel, formed in 2008, investigates the new GNSS-based architectures, with a focus on precision approach down to LPV-200 operations. GEAS identified ARAIM as the most promising system. The literature, produced through a series of studies, has analysed the performance of this new technique and has clearly shown that the potential of ARAIM architectures to provide the Required Navigation Performance for LPV 200. Almost all of the analysis was performed by simply studying a constellation's configuration 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 this paper, we will evaluate the ARAIM performance in simulated operational configurations. Aircraft flights can last for hours and on-board receivers don't always have a full view of the sky. 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. For this reason, the main objective of the algorithm developed in this research project is to analyse these shadowing effects and compute the performance of the ARAIM technique when integrated with a predicted flight path using different combinations of three constellations (GPS, GLONASS and Galileo), considered as fully operational.

Abstract: The approach and landing are the riskiest phases of flight and the probability of catastrophic accidents are rising due to reduced visibility in airport area. For increasing the safety and reliability of the aircraft at the approach and landing phase the Instrument Landing System, Precision Approach Radar, Microwave Landing System and Satellite Landing System can be used at instrument meteorological conditions. The advantage of the above mentioned systems consists in the fact that they are fulfill the technical conditions laid down by International Civil Air Organization or Federal Air Administration, the disadvantage is that they are can be used only on the permanent airports. The presented theoretical thesis deals with a suitability of new small area hyperbolic time difference of arrival passive surveillance system for aircrafts precision approach and landing on military airfield or heliport. Subject of the article is also: mathematical analysis, programming support and simulation on PC, measured position data transform into Instrument Landing System navigation signals, transmission of navigation signals to the aircraft and output data displaying on the airborne indicator.

Abstract: Research as part of thesis has a purpose to define the Global air navigation plan and its Aviation system block upgrades, as well as their potential impact on the global Air traffic management system. The aim of this research is the analysis and valorization of the Global Plan of air traffic navigation, an analytical review of the current Air traffic management systems, an analytical review of the Aviation system block upgrades modules strategy planning, and the description of all modules from the area of Optimal capacity and flexible flights. Results of the research will relate to the analysis of the implementation of the Aviation system block upgrades and to the achievement of the interoperability goals of the global Air traffic management systems.

Abstract: Airspaces around the world are introducing capabilities and infrastructure to handle higher traffic densities. Highly capable satellite based navigation is being adopted to help aircraft operate more efficiently in the future. Furthermore, Automatic Dependent Surveillance Broadcast (ADS-B), where aircraft and other users broadcast their precise position, velocity and intent, is being introduced to help manage these airspaces. This allows air traffic and other aircraft to have excellent awareness of the airspace users. Adoption of new systems and technologies will only intensify as future airspaces will have to handle more varied traffic such as unmanned aerial vehicles (UAV).

Abstract: A method, medium, and system to receive flight parameter data relating to a plurality of flights, the flight parameter data including indications of aircraft performance based navigation (PBN) capabilities, flight plan information, an aircraft configuration, and an airport configuration for the plurality of flights; assign probabilistic properties to the flight parameter data; receive accurate and current position and predicted flight plan information for a plurality of aircraft corresponding to the flight parameter data; determine a probabilistic trajectory for two of the plurality of aircraft based on a combination of the probabilistic properties of the flight parameter data and the position and predicted flight plan information, the probabilistic trajectory being specific to the two aircraft and including a target spacing specification to maintain a predetermined spacing between the two aircraft at a target location with a specified probability; and generate a record of the probabilistic trajectory for the two aircraft.

Abstract: Republic of Korea has established its performance-based navigation (PBN) implementation plan in 2010 for ensuring a smooth transition to PBN operations and relevant new flight procedures are being developed in accordance with the roadmap. Various Navigation aids (NAVAIDs) like global navigation satellite systems (GNSS), distance measuring equipment (DME), VHF omnidirectional range (VOR), inertial navigation system (INS) are used to support PBN procedures. Among them, GNSS would play a central role in PBN implementation. However, vulnerability of satellite navigation signals to artificial and natural interferences has been discovered and various alternative positioning, navigation and timing (APNT) technologies are under development in many countries. In this paper, we study whether continuous PBN operations can be achievable without GNSS signals. As a result, it shows that some of the domestic airports require the construction of APNT in the approach area.

Abstract: Most global navigation satellite system (GNSS) receivers cannot work in high dynamic scenarios because of poor navigation satellite acquisition in these environments. Hence, inertial navigation system (INS) is used to aid the GNSS signal acquisition and improve the acquisition capability of the receivers. In this paper, an ultra-tight integration system using the low-cost IMU is proposed to achieve navigation for high dynamic applications. To verify the effectiveness of the ultra-tight integration, an experiment system is built and a high dynamic scenario is simulated. The results prove that the designed ultra-tight integration system has perfect tracking and navigation performances for high dynamic applications.