Performance of data link communications in surface management operations

: This report represents evaluations of Data Link products and services in a simulated aviation operation. The study addresses key issues related to alerting schemes for Data Link messages, positioning of Data Link displays, and mode of presentation of Data Link messages. The comparison of response times of two alerting schemes, a nondistinctive alert and a nondistinctive alert with an annunciator lamp, did not favor one over another. The forward-mounted Data Link display led to less time required to respond to Data Link messages over aft-mounted, although this difference was not statistically significant. The aft-mounted display was also rated as higher in workload and lower in visibility by crews. Pilots preferred digitized speech over a text-only presentation of messages. The availability of Data Link significantly reduced the amount of controller radio communication with pseudopilots and simulator pilots. The subjective effort, workload of pilots, and fuel burn were not affected by the Data Link capability. However, pilots raised concerns about reduced confidence, safety, and situational awareness with Data Link.

Aircraft noise has been one of the top environmental issues at and near airports across the country because of its negative impact on communities. The growth of the nation's air transportation system is restricted predominantly due to regulations on limiting aircraft noise generated around airports. Reducing aircraft noise will lead to wider community acceptance of new or larger airports, lower airline operating costs by reducing noise quota fees, and increase air traffic growth through operating more flights. One of the most significant contributors to aircraft noise, structural vibrations caused by air flow across its frame, are high lift devices. A review of high lift devices, such as flaps, and methods to reduce their noise levels will be presented. Solution reviews will focus on reducing flap trailing-edge scattering and flap side-edge vortices.

Interconnection between multiple data link systems is an urgent problem for wireless control systems. Its difficulty lies in the fact that data link messages are multi-source heterogeneous, By analyzing its sub-domain characteristics, we constructs the data message domain ontology and establishes a data link message ontology model based on Bayesian network(DLMOBN). It includes the study of nodes, directed edges and node similarity probability distribution and so on, convert multi-source heterogeneous messages into mathematical models. We propose a data link message ontology mapping algorithm, the OWL syntax is used to formally describe the acquired domain ontology, extract useful information such as concepts, attributes, and instances, and then store the information in a preset data structure, k-means algorithm is used to cluster them to form “cluster”, which is used as a classification index to classify the similarity pair as a node in the Bayesian network, and pass the concept of the lower layer between nodes to the prior concept of the upper layer. The semantic distance, the attribute, the feature and other factors of the similar pair are used to calculate the semantic similarity. Finally, the final semantic similarity value is obtained by weighting. It is verified by experiments that the method improves the recall rate and precision, reduces the time complexity.

An Agent-Based Approach to Aircraft Conflict Resolution with Constraints

The Charles Stark Draper Laboratory, Inc. has developed the Air Transportation System Simulator (ATSS), an en-route air traffic simulator that can be used to conduct integrated safety, capacity, and economic analyses of national air transportation system advanced concepts. ATSS uses accurate geospatial models of the National Airspace System (NAS) sectors, en-route surveillance radars, and NAVAIDS. It simulates realistic information-states for Communication, Navigation and Surveillance (CNS) systems. The concept of an information-state captures the effects of compartmentalized or localized information: for example, an air traffic controller and an aircraft pilot may have different information about the current position and intended trajectory of an aircraft. Draper Laboratory developed ATSS in C++. Currently the run-time performance is memorybound; scenarios with 60K+ aircraft flight-plans can be run on a Windows XP desktop computer with 2GB RAM. Propagating an aircraft forward over a single simulated timestep takes 10-15msec on a 2GHz CPU. ATSS has been used for large-scale NAS-wide simulations of sector congestion, with scenarios of up to 120K flight-plans over a 24-hour period across the contiguous U.S.

Significant effort is being expended defining the requirements for unmanned aircraft to fly in the National Airspace System (NAS). The goal is for an unmanned aircraft to be able to file a flight plan and fly in the NAS with no more restrictions than those imposed on a manned aircraft. The result would be unmanned and manned aircraft flying together in the same airspace. Before this can occur, an unmanned aircraft must demonstrate that it can safely mingle with manned aircraft. The aircraft, control station and other components of the unmanned aircraft system (UAS) must complete the FAA's certification process, which determines that the UA can operate safely in the NAS. A key component of safe operations is communications. The pilot must be able to receive telemetry data from the aircraft and send commands to it. This is accomplished via a data link (the control link). In addition, he/she must be able to communicate with air traffic controllers who are using VHF voice radios to provide instructions to aircraft. In many cases the aircraft will relay the VHF voice traffic between the controller and the pilot. The communications path for the relay will be a data link between the aircraft and the pilot -referred to as the ATC communications link. A key element in getting a UAS certified will be demonstrating that the ATC communications and the Control links meet required communications performance (RCP) requirements. This paper explores the concept of a commercial organization providing the data link service needed for the UAS ATC communications and control links in the continental United States. The service provider would supply access nationwide and use aviation-protected spectrum in L-band. A concept of operations is presented along with a discussion of link access, protocols, and bandwidth limitations.

A simulation was conducted at the NASA Ames Research Center to compare how crews handled voice and data link air traffic control (ATC) messages in a single medium versus a mixed voice and data link ATC environment. The interval between ATC messages was also varied to examine the influence of time pressure. Results indicated that for messages sent via voice, transaction times were lengthened in the mixed media environment for closely spaced messages. The type of environment did not affect data link times. However, message times were lengthened in both single and mixed-modality environments under time pressure. Closely spaced messages also increased the number of requests for clarification of voice messages in the mixed environment and review log use for data link messages. Thus, when time pressure is introduced, the mix of voice and data link does not necessarily capitalize on the advantages of both media. These findings emphasize the need to develop procedures for managing communication in mixed voice and data link environments.

A number of Federal Aviation Administration (FAA) automation systems and developmental programs interoperate to support the day-to-day operations of the National Airspace System (NAS). The integration of New Entrants (NEs), such as Remotely Piloted Aircraft (RPA) 1 and Space Vehicle (SV) operations, into the NAS will require modification to the current state of automation. Examining the relevant operational, technical, and procedural implications of integrated NE operations, in addition to exploring the potential impacts of accelerated RPA usage on NAS dynamics, are critically important efforts necessary to understanding operational impacts to NAS systems and users. Our paper presents the potential impacts of RPA integration on two of these systems: En Route Automation Modernization (ERAM) and Traffic Flow Management System (TFMS). A significant component of the impact on NAS systems comes from flight plan and related data processing since all SVs and many RPAs will fly non-standard flight patterns (e.g., RPA loitering and grid search). The processes and details of the non-traditional flight routes, as well different RPA performance specifications, need to be considered as missions are overlaid on the national jet route structure. Of particular concern and interest are the changes in air traffic control (ATC) and air traffic management (ATM) systems and sub-systems needed to address air traffic controller workload and workload complexity concerns associated with NE activities. One potential accommodation approach, presented in this paper, is the use of Dynamic Airspace Configuration both for RPA routine operations and contingency events. Additionally, we present an RPA 1 In this paper, UAS and RPA are used interchangeably without intending any difference per se. It is noted that the U.S. DoD and ICAO use RPA while NASA and the FAA use UAS. demand forecast tool developed under a National Aeronautics and Space Administration (NASA) project. This tool will assist the FAA in meeting its objectives for accommodation of RPA by providing accurate demand forecast information.

This paper designs, simulates, and tests a potential Automatic Dependent Surveillance-Broadcast (ADS-B) space-oriented message set to improve situational awareness of commercial space vehicles inside the National Airspace System (NAS), and to minimize their impacts and potential hazards on the NAS. ADS-B is considered as the solution to integrate the future commercial space transportation system with the air transportation system. To accommodate future space flight operations in the NAS, a potential ADS-B space-oriented message set is proposed to be exclusively transmitted from space vehicles to other traffic and air traffic controllers. New data fields are defined in the message set to cover a space vehicle's entire flight profile. The formats of these new data fields are demonstrated in details. A simulation is created containing space vehicle and aircraft trajectories to test the functionality of the ADS-B space-oriented message set. The message set is encoded at the space vehicle site, transmitted from space vehicle to aircraft via the Universal Access Transceiver (UAT) datalink, and decoded at the aircraft site. The simulation eventually reaches a conflict scenario. By using the Closest Point of Approach (CPA) algorithm, the aircraft analyzes its own state vector and the space vehicle's state vector decoded from ADS-B messages to perform conflict detection. Sensitivity studies are conducted based on the CPA algorithm concentrating on three ADS-B system parameters, which are message update rate, data latency, and state vector accuracy.

Small regional airports present an underutilized source of capacity in the national air transportation system. This study sought to determine whether a 50 percent increase in national operations could be achieved by limiting demand growth at large hub airports and instead growing traffic levels at the surrounding regional airports. This demand scenario for future air traffic in the United States was generated and used as input to a 24-hour simulation of the national airspace system. Results of the demand generation process and metrics predicting the simulation results are presented, in addition to the actual simulation results. The demand generation process showed that sufficient runway capacity exists at regional airports to offload a significant portion of traffic from hub airports. Predictive metrics forecast a large reduction of delays at most major airports when demand is shifted. The simulation results then show that offloading hub traffic can significantly reduce nationwide delays.

Today’s National Airspace System (NAS) is approaching its limit to efficiently cope with the increasing air traffic demand. Next Generation Air Transportation System (NextGen) with its ambitious goals aims to make the air travel more predictable with fewer delays, less time sitting on the ground and holding in the air to improve the performance of the NAS. However, currently the performance of the NAS is mostly measured using delaybased metrics which do not capture a whole range of important factors that determine the quality and level of utilization of the NAS. The factors affecting the performance of the NAS are themselves not well defined to begin with. To address these issues, motivated by the use of throughput-based metrics in many areas such as ground transportation, wireless communication and manufacturing, this paper identifies the different factors which majorly affect the performance of the NAS as demand (split into flight cancellation and flight rerouting), safe separation (split into conflict and metering) and weather (studied as convective weather) through careful comparison with other applications and performing empirical sensitivity analysis. Additionally, the effects of different factors on the NAS’s performance are quantitatively studied using real traffic data with the Future ATM Concepts Evaluation Tool (FACET) for various sectors and centers of the NAS on different days. In this paper we propose a diagnostic tool which can analyze the factors that have greater responsibility for regions of poor and better performances of the NAS, thus providing vital information which can be used for suitable economic and environmental advantages.

In 2014, the Federal Aviation Administration (FAA) prioritized Performance-Based Navigation (PBN) capabilities of its Next Generation Air Transportation System (NextGen) and committed to implementing high-priority innovations within the next three years. For 2015, the commitments include the issuance of a national standard for PBN-enabled Equivalent Lateral Spacing Operation (ELSO) departures and ELSO implementations at airports throughout the United States (US) National Airspace System (NAS). Beginning in 2011, flight validations of ELSO-based reduced-divergence procedures at The Hartsfield-Jackson Atlanta International Airport (KATL) demonstrated operational benefits and validated the ELSO concept for the development of the standard. The standard will enable the NAS-wide use of PBN departure procedures with a reduced minimum divergence of 10 degrees instead of the 15 degrees currently required to conduct simultaneous parallel and successive departure operations. This paper describes the process, from inception to integration into the NAS that pioneered the first PBN-enabled reduced separation standard for departures. Further work to identify candidate airports for application and activities supporting the harmonization of PBN-based separation standards in the global air transportation system are also discussed.

NASA's Aeronautics Research Mission Directorate (ARMD) collaborates with the FAA and industry to provide concepts and technologies that enhance the transition to the next-generation air-traffic management system (NextGen). To facilitate this collaboration, ARMD has a series of Airspace Technology Demonstration (ATD) sub-projects that develop, demonstrate, and transitions NASA technologies and concepts for implementation in the National Airspace System (NAS). The second of these sub-projects, ATD-2, is focused on the potential benefits to NAS stakeholders of integrated arrival, departure, surface (IADS) operations. To determine the project objectives and assess the benefits of a potential solution, NASA surveyed NAS stakeholders to understand the existing issues in arrival, departure, and surface operations, and the perceived benefits of better integrating these operations. NASA surveyed a broad cross-section of stakeholders representing the airlines, airports, air-navigation service providers, and industry providers of NAS tools. The survey indicated that improving the predictability of flight times (schedules) could improve efficiency in arrival, departure, and surface operations. Stakeholders also mentioned the need for better strategic and tactical information on traffic constraints as well as better information sharing and a coupled collaborative planning process that allows stakeholders to coordinate IADS operations. To assess the impact of a potential solution, NASA sketched an initial departure scheduling concept and assessed its viability by surveying a select group of stakeholders for a second time. The objective of the departure scheduler was to enable flights to move continuously from gate to cruise with minimal interruption in a busy metroplex airspace environment using strategic and tactical scheduling enhanced by collaborative planning between airlines and service providers. The stakeholders agreed that this departure concept could improve schedule predictability and suggested several key attributes that were necessary to make the concept successful. The goals and objectives of the planned ATD-2 sub-project will incorporate the results of this stakeholder feedback.

This paper addresses topics concerning the development of future Unmanned Aerial Vehicles (UAV) so that they can operate safely within the community of the Federal Aviation Administration (FAA) and the International Civil Aviation Organization (ICAO). Studies by the Defense Science Board; the Office of Science and Technology; Government Accountability Office; and the Congressional Research Service: Library of Congress; have all emphasized that soon there will be a significant number of UAVs operating sideby- side with manned civil aircraft in the FAA’s National Airspace System (NAS). It is anticipated that future UAVs will start to perform many of the dull, dirty, and dangerous civilian missions. In 2006, about 600 UAVs are expected to be manufactured in the US alone. Therefore, there is an urgent need for developers of UAVs to understand safety certification for operations in the NAS, and that safety certification starts with the safety requirements; safety design; safe development process; safety verification; and safe operating procedures in the planned operational environment. This paper presents and discusses the experiences and lessons gained by the authors on the development of end-toend aviation safety; from the safety requirements to their final safety certification in the planned operational environment. The authors’ previous and ongoing works include the Global Navigation Satellite Systems (GNSS) systems such as the GPS; WAAS; LAAS; MSAS; GPS III; and different operational environments at different airports such as Incheon International Airport. The FAA started with the two traditional safety certifications processes: airborne system certification and ground system certification; governed mostly by Federal Aviation Regulations (FAR) and FAA’s Acquisition Management System (AMS), respectively. However, when FAA started to implement GNSS, the lines between airborne and ground systems became blurred, and as a result many current Communications, Navigation, Surveillance, and Air Traffic Management (CNS/ATM) systems have to follow both processes. We will also discuss the current Safety Management Systems being developed by both FAA and ICAO as an integrated, systematic, and harmonized approach and process to sort out the differing safety requirements from FAA, SAE-ARP, MIL-STD, RTCA, ASTM, ICAO, etc. to provide the eventual safe operations within the NAS. The discussion will then focus on the real world of institutional, operational, and technical issues for safety certification worldwide. Despite the numerous standards and guidance documents, many past safety analyses and studies were guided by best practices that had been used successfully in the past to streamline the process of providing all the required documentations and verifications. One such area is in the use of the “Integrity Panel of Experts” that had been used successful in the implementation of safety for the FAA’s Wide Area Augmentation System (WAAS) and Local Area Augmentation System (LAAS) programs. In many areas of the world, safety certification from a technical point of view is only the first step to achieving safety certification to fly in their national and sovereign airspace. Finally, we will show the first steps that UAV manufactures need to consider if they want their UAVs to be approved to fly safely in different national civilian airspace.

The U.S. national Air Traffic Management (ATM) system is today operating at the edge of its capabilities, handling the real-time planning and coordination of over 50,000 flights per day. This situation will only worsen in the years to come, as it is expected that U.S. air traffic will nearly double by the year 2025. There is a pressing need therefore for increasing capacity to meet future demand, improving safety, enhancing efficiency, providing additional flexibility to airline operators, and equitable consideration of multiple stakeholder needs in this complex dynamic system. In this paper, we present a scalable enterprise framework for multi-stakeholder, multi-objective model-based planning and optimization of air traffic in the national airspace system (NAS). The approach is based on an intelligent evaluation and optimization at the strategic and flight route levels. At the strategic level, we focus on separations between flights to improve airspace system performance. At the flight route level, we focus on identifying an optimal portfolio of flight paths within a planning horizon that trades-off a reduction in miles flown and a reduction in congestion. This framework not only considers system-level objectives, but also regards the impact of decisions on the principal stakeholders within the NAS. It is expected that this system will serve as a key decision-support tool to address future NAS scalability and reliability needs.