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Emerging urban air mobility operators propose to introduce extensive flight networks into metropolitan airspace. However, this airspace currently contains complex legacy airspace structure and flig...

This paper presents an algorithm for in-flight synthesis of near-optimal trajectory options sets in the presence of time-varying airspace constraints during the en route phase of an aircraft flight...

Unmanned Aircraft Systems (UAS) need to be able to comply with the Code of Federal Regulations Part 91 ‘see and avoid’ requirement. Detect and avoid (DAA) is an essential enabler for integrating UAS into the National Airspace System. A DAA system is a suite of sensors, trackers, and alerting and guidance algorithms that assists a remote pilot in maintaining separation from airborne traffic. Previous works have focused on operations transiting to and from Class A or special use airspace. More recent efforts have defined DAA system requirements for operations in and around the airport terminal environment. In continuation of this effort, this paper defines the DAA Terminal Area (DTA) size and switching technique for the DAA Well Clear (DWC) volume while transitioning between en route and the terminal area.

Unmanned aircraft systems must demonstrate a capability to sense and avoid air traffic as part of a layered conflict management system to enable safe operations in the National Airspace System. Dur...

To improve the safety and efficiency of air traffic control, it is important to detect any deviations (or maneuvers) of an aircraft from its planned route. In addition to the detection of maneuvers...

Present research in Air Traffic Management (ATM) is going towards improvement of airspace capacity, accessibility and efficiency while reducing the management costs and increasing the safety performance indicators. A 4D contract between an Airspace User (AU) and Air Traffic Control, in which aircraft should be located at a given time on a particular waypoint, opens a wide scope of applications for decision support tools (DSTs). This paper introduces a new modeling approach for a smooth safety nets transition within the high en-route airspace operations. The approach is based on a causal state space search as a response to some shortages in the collision avoidance events, resulted from a limited logic of Traffic alert and Collision Avoidance System (TCAS). It considers Enhanced TCAS (E-TCAS) that relies on an extended time horizon at the separation management level to define functionalities that will provide the most optimal resolution trajectories and remove the deadlock scenarios.

The problem of fitting the maximum number of aircraft into ATC sectors, keeping in mind aircraft separation and safety standards, area navigation direct routings and other factors, is known as the airspace capacity problem. Above the European airspace, a high density network of air traffic can be found which is determined by the workload of controllers. Constraint Programming (CP) is a powerful powerful paradigm for representing and solving a wide range of combinatorial problems. The PARTAKE project fosters adherence of air space user's trajectory preferences enhancing Trajectory Based Operations (TBO) concepts by identifying tight interdependencies between trajectories and introducing a new mechanism to improve aircraft separation at the hot spots by the mean of CP. The underlying philosophy is to capitalize present freedom degrees between layered ATM planning tools, when sequencing departures at airports by considering the benefits of small time stamp changes in the assigned slot departures.

Unmanned Aircraft Systems need to be able to comply with manned aviation ‘see and avoid’ separation requirements. A Detect and Avoid (DAA) System includes sensors, a tracker, and alerting and guidance algorithms that assist a remote pilot in maintaining separation from airborne traffic. To date, DAA system requirements development has focused on operations transiting to and from Class A or special use airspace. Current efforts are defining DAA system requirements for operations in and around terminal airspace. As a contribution to the current efforts, this paper highlights results from a Human in the Loop (HiTL) experiment comparing methods of changing from the transit-specific alerting and guidance criteria to proposed terminal-specific alerting and guidance criteria. It discusses operational considerations that are beyond the HiTL.

The Traffic Aware Planner (TAP) is a decision support automation tool for trajectory planning and optimization intended for use on today’s flight deck. Drawing from a variety of on- and off-board data sources, TAP employs a sophisticated trajectory optimization algorithm that provides the aircrew with fuel- and time-saving reroute recommendations that are free of known conflicts with traffic, special use airspace, and severe convective weather. As this kind of weather is a significant part of the pilot’s decision-making process while planning trajectory changes en route, a series of investigations has been conducted into the integration of weather data and associated functionality into the TAP software. This paper reviews the weather data sources and functionality that have been incorporated into TAP to date, along with experience gathered in the course of the design process.

The commercial use of space is not a new concept. Satellites have provided commercial services since the 1960s. However, the launch and recovery of space vehicles was dominated by State operators or under State Contract until the end of the last century. While commercial launches continue to increase, the international regulatory frameworks related to launch and reentry are fundamentally unchanged and are not structured to support a competitive commercial launch industry. This paper examines the regulatory gaps in the existing frameworks, particularly in the international domain. While there remain unresolved questions with regard to ICAO as it applies to suborbital flight, the ability of ICAO to develop standards and recommended practices for the portion of the operation that takes place in civil airspace is clear. These standards are necessary to ensure the safety of civil airspace for both traditional airspace users and launch operators, and the interaction of spaceports with civil airspace.

Modernization of the National Air Traffic Control System is on the horizon and with it the likely introduction of autonomous air vehicles into the national airspace. With the increase in air traffic to an already congested management scheme, the implementation of a decentralized control protocol may be the answer to replace the current classical centralized management system. Equipping each aircraft with the information necessary to navigate safely through integrated airspace becomes an information-sharing problem: How much information about other aircraft is required for a pilot to fly the gamut of a heavily populated airspace safely? What paradigm shifts may be necessary for safe and efficient use of available airspace? This paper describes the development of a tool for testing alternative traffic management systems—centralized and decentralized—in the presence of uncertainty. Applying a computational fluid dynamics–inspired approach to the problem both creates a simulation tool to model the movement of traffic within the airspace and allows study of the effects of interactions between vehicles. With incorporation of a model based on smoothed particle hydrodynamics, discrete particle aircraft each carry a set of unique deterministic and stochastic properties. With this model, aircraft interaction can be studied for better understanding of how variations in the nondeterministic properties of the system affect its overall efficiency and safety. The tool is structured to be sufficiently flexible to allow incorporation of different governing equations (right-of-way rules) for aircraft traffic management.

New technical standards for Unmanned Aircraft Systems (UAS) detect and avoid (DAA) systems mark recent progress toward realizing the goal of full integration of UAS into the National Airspace System (NAS). The DAA system is intended to provide a means of compliance with operating regulations that required pilots on board manned aircraft to remain "well clear" of other aircraft which is accomplished through out-the-window visual acquisition of other aircraft and application of a subjective judgment of safe separation. The requirements for the DAA system, including the specification of a DAA well clear threshold as well as functional requirements for detecting, tracking, alerting and guidance processing, and displays, are specified in DO-365, Minimum Operational Performance Standards (MOPS) for DAA Systems developed within RTCA (Radio Technical Commission for Aeronautics) Special Committee 228 (SC-228). Intended as the first in a series of phased versions, these requirements are frequently referred to as the "Phase 1" DAA system. The Phase 1 DAA system is limited for use by aircraft transitioning to and from Class A or special use airspace, through Class D, E, and G airspace. In particular, the Phase 1 DAA MOPS are not intended for terminal airspace operations, a critical gap for enabling a full range of UAS operations. The application of the Phase 1 DAA system and DAA well clear threshold within the terminal area is predicted to result in a high number of unnecessary alerts when the UAS is safely separated from other traffic. The goal of the present study was to examine pilot performance and operational issues related to the operation of the Phase 1 DAA system in a terminal area. This experiment was intended as an exploratory study that would be used to inform the development of a new terminal area-specific DAA well clear definition, and associated alerting and guidance requirements. The two main objectives of this study were to: 1) characterize pilot behavior in the terminal environment with the Phase 1 DAA system, and 2) investigate the effect of modifications to the Phase 1 DAA alerting and guidance structure. In particular, the authors were interested in determining whether the removal of specific alerting and guidance levels, without changing the DAA well clear definition or alerting thresholds, would impact pilot performance while conducting terminal operations. The results indicate that the Phase 1 well clear definition and alerting and guidance resulted in frequent alerting that degraded pilots' ability to discriminate between encounters where another aircraft was safely separated versus when a maneuver was necessary. The resulting impact on pilot performance was slower response times and higher frequency and severity of losses of DAA well clear compared to those observed for experiments examining pilot performance in the en route environment. There was no significant effect of alerting and guidance display configuration on pilot performance.

Routine access to non-segregated airspace is a key enabler for the civilian Unmanned Aircraft System (UAS) industry. Approvals for UAS operations in this airspace are contingent on the provision of a safety case, which details how the risk of a Mid-Air Collision (MAC) accident will be managed to an acceptable level. There is no accepted framework for structuring operational safety cases for UAS and this gives rise to a number of challenges to the application of the regulation by “safety target” approach. Further, a wide range of controls has been proposed for mitigating the risk, however the effectiveness of the controls is not known. A reconciliation and extension of existing causal models describing the MAC accident sequence is provided in this paper. A barrier bow tie model is developed as a means for structuring the safety case for generic UAS operations in non-segregated airspace. The model is applied to the classification of over 50 commonly used risk controls and the relationship between the control and the manner in which the reduction in MAC risk is achieved is determined. A case-study application is also presented validating the utility of the tool in the development and communication of safety cases for UAS operations in civilian airspace.

The automatic dependent surveillance-broadcast system serves a dual role for general aviation operators, allowing integration with modern surveillance systems and providing an uplink of traffic, we...

As unmanned aircraft systems (UAS) become more important to the US military and other users, the pressure to allow them to fly in the national airspace increases. The greatest impediment to this is...

The Dynamic Weather Routes (DWR) tool continuously and automatically analyzes active flights in en route airspace and finds simple route corrections to achieve more time- and fuel-efficient routes around convective weather. A strong partnership between the National Aeronautics and Space Administration (NASA), American Airlines (AA), and the Federal Aviation Administration (FAA) has enabled testing of DWR in real-world air traffic operations. NASA and AA have been conducting a trial of DWR at AA’s Integrated Operations Control Center in Fort Worth, Texas since July 2012. This paper describes test results based on AA’s use of DWR for their flights in and around Fort Worth Center (ZFW). Results indicate an actual savings of 3,949 flying minutes for 624 AA revenue flights from January 2013 through December 2014. Of these, 101 flights each indicate a savings of 15 min or more. Potential savings for all flights in ZFW airspace, corrected for savings flights achieve today through normal pilot requests and contro...

As the operations of airspace is becoming more and more complex, the restricted area has become one of the most important threat to flight safety. In order to avoid the conflict between aircraft and restricted area and ensure the route’s distance optimal, an efficient and safe flight plan is determined by route planning.

International parcel services as well as online retailers are planning to install their own delivery drone fleets in the foreseeable future. Given the typical volumes of such businesses it is likely that this poses huge demands on the urban airspace in terms of capacity and conflict resolution. Current UTM concepts devise means to automatically detect and solve conflicts in smaller scales. However, it is yet unanswered to what degree a conflict-free operation of hundreds or thousands of drones occupying the same airspace is possible. In this paper we present a generic simulation framework that can load a given urban airspace with a specified demand or frequency of delivery drones. Based on actual street map data the user can specify a delivery area, a regular or randomized delivery schedule and a number of logistic centers to start from. Random destinations are then picked from the street maps and drones are scheduled to service these destinations. Further, the system analyzes the pre-planned drone schedule for conflicts and tries to resolve these conflicts without delaying individual drones too much. We detail statistics on how responsive the system is to unexpected events like emergency helicopters. The results give first insights, to what degree automatic de-conflicting solutions may work in urban areas.

Air traffic demand around the world is forecasted to increase, and will therefore put additional strain on the air traffic management system currently used. In the sectorless airspace concept, air traffic controllers are no longer tied to sectors of airspace, but to specific flights. Each controller will maintain radio contact with several aircraft and guide them from the entry to the exit of the airspace. This is a move away from the current geographical attachment of one sector to one controller. For this concept to work, each controller will have a unique voice communication frequency, and this frequency has to propagate to the extreme ends of the airspace. Furthermore, a free-route sectorless airspace has the capacity to support many more aircraft than the current system. Consequently, the number of controllers and indirectly, the number of voice communication frequencies required, will increase as well. This paper presents several restrictions on VHF frequency usage and discusses the problem with regards to the VHF frequencies allocation arising from the implementation of a sectorless airspace. It also provides a preliminary analysis of the VHF voice communication capacity through a simple mathematical formulation. Using a simple concentric buffer zone in which the repeated use of the same frequency is prohibited, the current voice communication infrastructure is estimated to only support up to 5% or 18% of the maximum capacity of a sectorless airspace. Finally, several possible solutions such as adaptations to the VHF system, digital radio, and satellite systems are briefly reviewed.

We present a straw man architecture that could serve as the basis of a future National Airspace System where autonomous aircraft are controlled by autonomous controllers. Such an architecture is characterized by geofenced areas that have equipage constraints as well as aircraft volume constraints, where these geofenced areas are computed dynamically. Airspace structure is largely avoided, but instead is dynamically computed as the airspace loading changes. The dynamically computed structure is based on the airspace system's current state as well as its broadcast intention from all participants, with allowances for mishaps and other system failures. The safety margin of the dynamic structure is continuously computed to provide guidance to the control algorithms that regulate airspace loading. Details of this architecture are presented as well as its evaluation method.

Increasingly crowded airspaces are bringing the attention of the aviation community since diverse users try to make use of a common airspace. The challenge is to identify and implement technologies to effectively but also efficiently manage an integrated multi-aviation airspace. This paper briefly presents a comprehensive synopsis of efforts to unify air navigation regulations so that the airspace can be effectively shared by multiple aviation pilots and aircraft. It recalls proposals to enable aviation sectors to coexist in the same airspace. The focus of this paper is on insights into Knowledge Technologies (KTs) to facilitate procurement and management of a shared multi-aviation airspace. It discusses challenges and opportunities when implementing KT solutions to facilitate the integration of different aviation capabilities for a shared airspace. The analysis presented selectively explores software engineering for bottom-up/top-down integration along with artificial intelligence traits such as knowledge representation. Concluding remarks and the way forward to foster KT solutions for integration of multiple aviation in a single airspace are also presented.

The plenary talk at DASC 2016 by Dr. Parimal Kopardekar, the Principal Investigator of NASA UTM program, highlighted understanding the role of volume, noise and spectrum considerations in airspace demand-capacity modeling as the three requests from UTM developers to the avionics research community [1]. This paper proposes initial answers to all three requests, for the case of unmanned aerial vehicles (UAVs) operating in low-altitude uncontrolled airspace above populated areas: we estimate airspace capacity under several metrics centered on traffic volume manageability, drones noise pollution and spectrum demand. Our work aids in bridging regulators and the industry, by providing policy makers with decision support tools which help to quantify technological requirements which the manufacturers must follow in order to ensure seamless operation of small unmanned aerial systems (sUAS) in an urban airspace.

The National Aeronautics and Space Administration Unmanned Aircraft Systems Integration in the National Airspace System Project has conducted a series of flight tests intended to support the reduction of barriers that prevent unmanned aircraft from flying without the required waivers from the Federal Aviation Administration. The 2015 Flight Test Series 3, supported two separate test configurations. The first configuration investigated the timing of Detect and Avoid alerting thresholds using a radar equipped unmanned vehicle and multiple live intruders flown at varying encounter geometries. The second configuration included a surrogate unmanned vehicle (flown from a ground control station, with a safety pilot on board) flying a mission in a virtual air traffic control airspace sector using research pilot displays and Detect and Avoid advisories to maintain separation from live and virtual aircraft. The test was conducted over an eight-week span within the R-2508 Special Use Airspace. Over 200 encounters were flown for the first configuration, and although the second configuration was cancelled after three data collection flights, Flight Test 3 proved to be invaluable for the purposes of planning, managing, and execution of this type of integrated flight test.

The Federal Aviation Administration's (FAA) long-term vision for full and safe integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS) includes UAS operations in a non-segregated environment where manned and unmanned aircraft share airspace. NAS air traffic services and resources are provided, as needed, with appropriate technology, infrastructure, procedures and policies in place to ensure safe and efficient operations.

The goal of the integration of Unmanned Aircraft Systems (UAS) in the National Airspace System (NAS) is to achieve “file-and-fly” access to all classes of airspace. This means the UAS will fly without limitations or waivers in airspace shared with other manned and unmanned aircraft. In the case of large UAS operating in a similar manner to transport category aircraft in terminal, en-route and oceanic/remote environments, this includes the ability to perform area navigation.

The US Class E airspace from 60,000 to 100,000 feet is currently designed for military operations, however, new commercial operations, including unmanned free balloons, high endurance UAS and commercial space operations (including manned free balloons) are beginning to occupy that airspace, and will require air traffic services. Technological developments in CNS will not only enable IFR services in this airspace, but could provide a CNS roadmap for the complete integration of commercial space operations in the National Airspace System.

In order to define system requirements for avionics used for low-altitude, small, Unmanned Aircraft Systems (sUAS) operations, the functions those avionics must perform need to be identified. Since avionics are an important contributor to ensuring the safety of sUAS operations, one way to determine what functions are necessary is to identify the operational hazards Unmanned Traffic Management (UTM) avionics must help mitigate. SUAS operations have the potential to pose a risk to persons onboard other aircraft, as along with persons and property on the ground. Thus, the primary safety objectives are to prevent collisions between sUAS and manned aircraft, as well as collisions between sUAS and persons or property on the ground. Together with procedural and operational mitigations, UTM avionics would need to sufficiently mitigate operational hazards that could potentially lead to such collisions. However, depending on the operation, the type and level of exposure to such hazards will vary, and as a result the level and type of mitigations that UTM avionics need to provide will differ. Three operational categories are proposed in this paper, each with a specific set of operational hazards that have the potential to negatively impact safety. Category 1 operational hazards consist of collisions with fixed, or nearly-fixed, ground-based obstacles, including humans. Other operational hazards are excluded by nature of the operation or the operational environment. For example, a Category 1 operation may be the within line-of-sight inspection of a cell tower, where the presence of manned aviation can be excluded due to the presence of the cell tower. Category 2 includes Category 1 hazards as well as moving (ground-based) vehicles and other sUAS. An example would be a Beyond-Line-of-Sight (BLOS) inspection of a powerline, where manned aviation can still be excluded, but where there is a potential of encountering another sUAS. Category 3 further includes manned aviation — air transport as well as “Low and Slow” aircraft — in addition to Category 1 and 2 hazards. An example of this type of operation would be a BLOS inspection of a pipeline; the operation could no longer “take credit” of any infrastructure to mitigate the possible hazard of manned aviation. High-level system requirements for equipment that helps in the mitigation of operational hazards are derived for each operational category. Category 3 operations are of particular interest since they have the potential of interacting with manned aviation either within the UTM airspace, or during operations near the interface between the UTM airspace and the airspace immediately above it (usually Class G or E airspace). This introduces additional system requirements related to the interoperability of the two traffic management systems, which are explored in the last section of the paper. Specifically, if the sUAS is transmitting position and velocity information, that information must meet accuracy and integrity requirements in order for it to be used in separation assurance functions. If the sUAS uses position information received from another aircraft to execute collision avoidance maneuvers, those maneuvers must be coordinated with the maneuvers that are being executed onboard the manned aircraft. Similarly, if the sUAS uses a navigation system to ensure conformance to certain airspace and routes, this navigation system becomes a safety critical component, and must thus meet applicable performance standards. The derivation of lower-level system requirements for specific operations within each category is left as future work.

As part of the Single European Sky Airspace Research program (SESAR) a new operational instrument is being developed: the Free Route Airspace (FRA). FRA defines airspace areas where user can decide about the best performance routes, not subjected to airways or mandatory crossing points. Currently, 11 FRA projects are been deployed specially in low density areas and low density time periods. Long-term benefits for one single FRA can account for saving up to 32,000 nautical miles per day, which may represent around 100,000 Euros savings per days. In this paper we assess the benefit figures with the opinions of the involved air traffic controllers. They point to the challenges to be overtaken before extending the future FRA. An important issue, raised by the air traffic controllers, was the importance of the support tools. Also important are the previous training and a full FRA deployment.

The purpose of Air Transportation is to move people and cargo safely, efficiently and swiftly to their destinations. The companies and individuals who use aircraft for this purpose, the airspace users, desire to operate their aircraft according to a dynamically optimized business trajectory for their specific mission and operational business model. In current operations, the dynamic optimization of business trajectories is limited by constraints built into operations in the National Airspace System (NAS) for reasons of safety and operational needs of the air navigation service providers. NASA has been developing and testing means to overcome many of these constraints and permit operations to be conducted closer to the airspace user's changing business trajectory as conditions unfold before and during the flight. A roadmap of logical steps progressing toward increased user autonomy is proposed, beginning with NASA's Traffic Aware Strategic Aircrew Requests (TASAR) concept that enables flight crews to make informed, deconflicted flight-optimization requests to air traffic control. These steps include the use of data communications for route change requests and approvals, integration with time-based arrival flow management processes under development by the Federal Aviation Administration (FAA), increased user authority for defining and modifying downstream, strategic portions of the trajectory, and ultimately application of self-separation. This progression takes advantage of existing FAA NextGen programs and RTCA standards development, and it is designed to minimize the number of hardware upgrades required of airspace users to take advantage of these advanced capabilities to achieve dynamically optimized business trajectories in NAS operations. The roadmap is designed to provide operational benefits to first adopters so that investment decisions do not depend upon a large segment of the user community becoming equipped before benefits can be realized. The issues of equipment certification and operational approval of new procedures are addressed in a way that minimizes their impact on the transition by deferring a change in the assignment of separation responsibility until a large body of operational data is available to support the safety case for this change in the last roadmap step.This paper will relate the roadmap steps to ongoing activities to clarify the economics-based transition to these technologies for operational use.

The Dynamic Weather Routes (DWR) tool is a ground-based trajectory automation system that continuously and automatically analyzes active in-flight aircraft in en route airspace to find simple modifications to flight plan routes that can save significant flying time, while avoiding weather and considering traffic conflicts, airspace sector congestion, special use airspace, and FAA routing restrictions. Trials of the DWR system have shown that significant delay savings are possible. However, some DWR advised routes are also rejected by dispatchers or modified before being accepted. Similarly, of those sent by dispatchers to flight crews as proposed route change requests, many are not accepted by air traffic control, or are modified before implementation as Center route amendments. Such actions suggest that the operational acceptability of DWR advised route corrections could be improved, which may reduce workload and increase delay savings. This paper analyzes the historical usage of different flight routings, varying from simple waypoint pairs to lengthy strings of waypoints incorporating jet routes, in order to improve DWR route acceptability. An approach is developed that can be incorporated into DWR, advising routings with high historical usage and savings potential similar to that of the nominal DWR advisory. It is hypothesized that modifying a nominal DWR routing to one that is commonly used, and nearby, will result in more actual savings since common routings are generally familiar and operationally acceptable to air traffic control. The approach allows routing segments with high historical usage to be concatenated to form routes that meet all DWR constraints. The relevance of a route's historical usage to its acceptance by dispatchers and air traffic control is quantified by analyzing historical DWR data. Results indicate that while historical usage may be less of a concern to flight dispatchers accepting or rejecting DWR advised route corrections, it may be important to air traffic control acceptance of DWR routes.

This paper advocates for a specific design approach, based on simple principals, yet addresses challenges faced by the system engineers when designing complex data and information infrastructure. The document provides guidance for breaking out various work elements in the overall network architecture design, so that communication systems are conceived and effectively realized regardless of their location, size and local specifics. Although targeted at the Global Airspace System (GAS) and National Airspace System (NAS), this framework can be applied to any network-centric architecture.