Integration Of Unmanned Aircraft Systems Research Articles

From the Editors of the Special Issue on Urban Air Mobility and UAS Airspace Integration: Vision, Challenges, and Enabling Avionics Technologies

The integration of unmanned aircraft systems (UAS) in all classes of airspace represents, at the same time, an evolutionary and a revolutionary step in air transport operations. As a result, new concepts have emerged for UAS traffic management to support the anticipated traffic density growth and the need for safe beyond visual line-of-sight operations. Closely linked with these developments, urban/advanced air mobility (UAM/AAM) has appeared as a new and disruptive dimension for aviation, potentially enabling mobility of goods and people at a different scale compared with current operations, while also emphasizing the need of seamless integration with the existing air traffic management (ATM) framework. These UAS capabilities are reshaping the future of aviation, but also challenge traditional paradigms, requiring significant advances both in technologies and regulations, while keeping strong links with public communities and the perception of societal benefits. As an example, a key role is played by the progress of communications, navigation and surveillance technologies, such as sense-and-avoid and global navigation satellite systems-resilient, alternate position, navigation, and timing systems, and by the seamless integration of airborne and ground infrastructure within a cyber-aware context. Similarly, significant restructuring of the existing regulatory framework is needed to ensure that the integrity and safety of the AAM/ATM integrated airspace is maintained while enabling autonomous operations with higher technological flexibility and refresh rates.

The Integration of Unmanned Aircraft System (UAS) in Current Combat Operations

Abstract The accelerated evolution of Unmanned Aircraft System (UAS) leads to the need to integrate UAS into operations, sometimes with unexpected results. In particular for special operations forces, reconnaissance, surveillance and deep precision strike, will remain main missions for which the utilization of UAV it is becoming critical. Whether we talk about missions such as: direct actions, objective security, force close protection, Imagery intelligence (IMINT) close fire support, maneuver, or combat resupply, UAS can cover a large spectrum of potential missions. However, when integrating UAS in military operations, the most intriguing developments are the impacts on the decision-making process, on the balance between the human factor and artificial intelligence, on force structure design.

Swarm-Based Optimization of Final Arrival Segments Considering the UAS Integration in the National Airspace System

In the past few years, there has been a growth in Unmanned Aircraft Systems (UAS) numbers in segregated airspace. However, although there is an interest in integrating large UAS in the National Airspace System (NAS), safety challenges regarding this insertion arise from the inclusion of new ways of reaching unsafe states. Although UAS may be used in different situations and brings several advantages to the airspace (e.g., efficiency), it may bring uncertainties due to the lack of familiarity of Air Traffic Controllers (ATCos) in these operations. Furthermore, the Terminal Maneuvering Area (TMA) is a critical control area generally established at the confluence of Air Traffic Service (ATS) routes in which the aircraft tend to be closer to each other. Besides, defining a final arrival segment for a set of aircraft in a complex environment is challenging. Thereupon, the main objective of this research is to propose a parallel swarm-based method for optimizing final aircraft arrival segment design (i.e., routes that connect the final sector to the Initial Approach Fix - IAF) considering the presence of aircraft of multiple Technology Maturity Levels (TML) - including the UAS. This is conducted from two perspectives: ATCo workload (which is related to safety) and sequencing duration (which is related to efficiency). Furthermore, different phases of UAS integration are considered using the Technology Maturity Levels (TMLs). Finally, the solutions consider airspace restrictions (e.g., minimum separation between aircraft and bad weather conditions). The experiments conducted show that this approach can build safe and efficient solutions, even in situations with many aircraft.

ADS-B Performance Monitoring and Potential Electromagnetic Interference

The integration of unmanned aircraft systems (UAS) into the air traffic management will be very demanding. Surveillance equipments based on Automatic Dependent Surveillance-Broadcast (ADS-B) contribute a significant role for maintaining separations between both UAS and aircraft in order to maintain the requirements of aviation safety and airspace integrity. Performance analysis of ADS-B equipments related to signal quality and potential Electromagnetic/Radio Frequency Interference is very important to mitigate the failure risk in air traffic management. This paper discuss performance test analysis of ADS-B based surveillance equipments related to the most importance performance parameter namely the continuous reception of messages in terms of message drops and probability of update interval message receptions. Another performance test related to electromagnetic emission of ADS-B based surveillance equipments is conducted in order to mitigate potential RF interferences.

Initial Assessment of Unmanned Aircraft System Characteristics Required to Fill Data Gaps for Short-term Forecasts: Results from Focus Groups and Interviews

The integration of unmanned aircraft systems (UAS) into the weather surveillance network must be guided by the data needs of the principal stakeholders. This work aims to assess data needs/gaps for short-term forecasts (<1-day lead time) issued by the National Weather Service (NWS) and then identify UAS characteristics required to fill these gaps. Results from focus groups and interviews of forecasters in the central United States are presented. Participant verbal responses were coded and then categorized into a set of 25 unique features. Each feature was classified according to four characteristics: 1) environmental properties that need to be measured to represent a given feature, 2) flight type (vertical profile, horizontal transect, and/or survey) 3) flight height required to measure the environmental properties, and 4) relevance of feature to the forecasting of deep convection. Findings indicate the majority of identified features require measurement of typical state variables (temperature, moisture, and wind), but more than a third require visual imagery. Almost all of the features require either survey flight operations or vertical profiles. Additionally, 96% of the features require observations collected below 1000 m. Nearly two-thirds of the features are associated with deep convection. This work represents the first step towards establishing how UAS could be used to fill data gaps that exist for short-term forecasts issued by the NWS. The results stand alone in demonstrating the potential applications of UAS from the perspective of operational forecasters and have also informed ongoing efforts to develop a nationwide survey of forecasters.

Integration of Unmanned Aircraft Systems into the National Airspace System-Efforts by the University of Alaska to Support the FAA/NASA UAS Traffic Management Program

Over the past decade Unmanned Aircraft Systems (UAS, aka “drones”) have become pervasive, touching virtually all aspects of our world. While UAS offer great opportunity to better our lives and strengthen economies, at the same time these can significantly disrupt manned flight operations and put our very lives in peril. Balancing the demanding and competing requirements of safely integrating UAS into the United States (US) National Airspace System (NAS) has been a top priority of the Federal Aviation Administration (FAA) for several years. This paper outlines efforts taken by the FAA and the National Aeronautics and Space Administration (NASA) to create the UAS Traffic Management (UTM) system as a means to address this capability gap. It highlights the perspectives and experiences gained by the University of Alaska Fairbanks (UAF) Alaska Center for Unmanned Aircraft Systems Integration (ACUASI) as one of the FAA’s six UAS test sites participating in the NASA-led UTM program. The paper summarizes UAF’s participation in the UTM Technical Capability Level (TCL1-3) campaigns, including flight results, technical capabilities achieved, lessons learned, and continuing challenges regarding the implementation of UTM in the NAS. It also details future efforts needed to enable practical Beyond-Visual-Line-of-Sight (BVLOS) flights for UAS operations in rural Alaska.

Modeling framework for analyzing midair encounters in hybrid airspace where manned and unmanned aircraft coexist

The integration of unmanned aircraft system into nonsegregated airspace raises safety concerns of midair encounters in the hybrid airspace where manned and unmanned aircraft coexist. This paper aims at developing a new modeling framework with improved modeling capability and feasibility for analyzing the midair encounters in hybrid airspace. This modeling framework includes models of different components (airspace, human pilot, manned aircraft, unmanned aircraft, etc.) involved in midair encounters. As a key component, human pilot is modeled to contain different information processing stages which are perception, decision making and response. Meanwhile, the modeling framework is designed to provide quantitative measures of midair encounters in hybrid airspace, and further uses “Equal Level of Safety” criterion to evaluate the validity of the integration of the unmanned aircraft system. Finally, the feasibility and effectiveness of the proposed modeling framework are demonstrated through simulation studies.

Overview of acoustic detection for counter unmanned aircraft systems

Integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS) is currently a major problem for government and industry. The detection of unauthorized UAS activity is a concern. There is a need for effective low-cost sensor technology to detect and track unauthorized UAS operations. Acoustic sensor systems have potential to improve counter UAS (C-UAS) sensing capabilities at greatly reduced cost relative to traditional sensors such as radar and optical systems, but the commercially available acoustic sensing technology is still lacking. The MITRE Corporation has been a leader in advising the United States’ Federal Government on the issues around integration of UAS into the NAS and C-UAS technologies. Research done by MITRE on acoustic sensing of UAS will be presented. The current state of commercially available acoustic sensor systems will be briefly reviewed. Recommendations that MITRE has developed on how to design acoustic sensor systems for C-UAS will be discussed. Future research directions in topics such as acoustic beamforming, array design, and outdoor sound propagation will be recommended. Approved for Public Release; Distribution Unlimited 18-4035

Impact of 2018 FAA Reauthorization Act on UASs

The commercial unmanned aircraft industry exists in a rapidly evolving and uncertain environment, with a multitude of well-established, well-financed stakeholders in associated industries each vying to influence that environment. Although influence can come in many forms, Congress holds the ultimate power, and gives agencies like the Federal Aviation Administration (FAA) a recurring authorization to regulate air travel and associated research. On October 5, 2018, this authorization was extended until 2023 In a variety of draft forms since introduced by Senator Schuster in June of 2017, the FAA Reauthorization Act of 2018 grants an additional 5 years to the FAA, and with it a multitude of new directives related to Unmanned Aircraft Systems (UASs). The House and Senate had versions under review for over a year, each with unique amendments that impact UAS operations and address many of the concerns of stakeholders, but not all of them will assist the industry in its efforts to integrate within the National Airspace system with manned traffic. Some like the Department of Homeland Security, local law enforcement agencies, and commercial passenger operators all have differing interests that may slow the growth and integration of UASs. With this final bill, the industry gets the opportunity to operate as it wishes in some areas, but loses some of the freedoms it once had.

Sense and avoid for unmanned aircraft systems

Sense and avoid (SAA) represents one of the main roadblocks to the integration of unmanned aircraft systems (UAS) operations by aviation authorities around the world. This tutorial outlines and reviews the substantial breadth of SAA architectures, technologies, and algorithms. Starting from a discussion about what constitutes a UAS and how it is different than manned aircraft, basic SAA definitions and taxonomies are discussed. The SAA process is dissected into three fundamental tasks, defined as sensing, detecting, and avoiding, which are discussed in detail. The tutorial concludes with a summary of the regulatory and technical issues that continue to challenge the progress on SAA, as a key component of reliable UAS operation in civil aviation authorities (CAAs) around the world.

Unmanned Aircraft Systems Airspace Integration: A Game Theoretical Framework for Concept Evaluations

The focus of this paper is to present a game theoretical modeling framework for the integration of unmanned aircraft systems into the National Airspace System. The problem of predicting the outcome of complex scenarios, where manned and unmanned air vehicles coexist, is the research problem of this work. The fundamental gap in the literature is that the models of interaction between manned and unmanned vehicles are insufficient: 1) They assume that pilot behavior is known a priori, and 2) They disregard pilot reaction and the decision-making process. The contribution of this paper is to propose a realistic modeling framework that will fill this gap. The foundations of the proposed method are formed by game theory, which investigates strategic decision making between intelligent agents; bounded rationality concept, which is based on the fact that humans cannot always make perfect decisions; and reinforcement learning, which is shown to be effective in human learning in psychology literature. An analysis of integration is conducted using an example scenario in the presence of manned aircraft and fully autonomous unmanned aircraft systems equipped with sense-and-avoid algorithms.

Unmanned Aircraft System Sense-and-Avoid Integrity and Continuity Risk

This paper describes new methods to reach safety targets for sense-and-avoid sensors for unmanned aircraft systems by evaluating integrity and continuity risks. These methods can be used to set sensor requirements. The closest-point-of-approach distance and time to closest point of approach, , are used to measure the hazards associated with the intruder aircraft. The contribution to knowledge in this paper is a new method that uses hazard state estimates and estimate error to establish 1) the integrity risk of the sense-and-avoid system not detecting imminent loss of self-separation, and 2) the probability of false alert, the flight-path continuity risk. A sensitivity analysis evaluates the impact on integrity and continuity of sensor noise, range, and sample interval. The methods described in this paper can be used to set potential sense-and-avoid sensor requirements for unmanned aircraft system integration into the National Airspace System.

An Examination of Unmanned Aircraft Systems Pilots’ Interaction with Air Traffic Control while Responding to Detect and Avoid Conflicts

New performance standards for a detect and avoid (DAA) system are being developed to support the broader integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS). One subset of these performance standards will address the minimum DAA display requirements to support pilot performance on maintaining well clear of other aircraft. These performance standards must take into account the current air traffic control (ATC) operational environment. In particular, the DAA system, and pilots’ interactions with that system, must account for the requirement for pilots to request a clearance for deviations from their approved instrument flight rules route. A series of human-in-the-loop (HITL) experiments were conducted to help identify the minimum information requirements for DAA displays. As part of these experiments, several pilot-ATC interaction metrics were collected, such as the amount of time it took pilots to request an ATC clearance prior to executing a maneuver to maintain well clear after the appearance of a DAA alert, and the proportion of time that pilots received an ATC clearance prior to maneuvering. The results indicate that while there was no observed effect of different display configurations on pilots’ interactions with ATC, these interactions were affected by the combination of alerting and operational procedures. When pilots received an unambiguous alert to potential well clear violations in conjunction with operational procedures that specified the expected actions to various alert levels, the time that it took for pilots to notify ATC of he need to maneuver dropped substantially, and the rate of obtaining a clearance increased. The implications of these results for developing performance standards for DAA are discussed.

Survey of Operators’ Unmanned Aircraft Systems Experience

The routine integration of unmanned aircraft systems (UAS) into controlled airspace is a pressing challenge around the world. In order to identify what information surveillance systems need to detect and display about the UAS, air traffic controllers and pilots were surveyed. Participants were asked a wide range of questions regarding their experience with UAS and information requirements under different conditions. This paper focuses on understanding operators’ previous experiences with UAS. Close to 60% of controllers and 42% of pilots reported having had some form of experience with UAS. Approximately the same proportion of controllers reported UAS operating in airspace designated for UAS operations as those reporting operations in low and high density regions of airspace and near standard flows in their airspace.

Sense and avoid requirements for unmanned aircraft systems using a target level of safety approach.

One of the most critical challenges to full integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS) is the requirement to comply with CFR 14 Part 91.113 to "see and avoid" other aircraft. Various attempts have been made to develop systems to "sense and avoid" other aircraft so UAS can comply with the intent of the regulation. This article proposes a framework to develop effectiveness requirements for any SAA system by linking UAS characteristics and operating environments to midair collision risk quantified by a fatality rate. The framework consists of a target level of safety (TLS) approach using an event tree format. Safety has been identified as the most important consideration in the UAS integration process. While safety can be defined in many ways, the authors propose using a fatality rate metric that follows other statistics used in the industry. This metric allows for the use of a TLS approach to the development of SAA requirements for system certification. Failure to adequately link system requirements to safety could result in the implementation of SAA systems that either do not adequately mitigate the risk associated with UAS operations or are overdesigned, resulting in increased cost and complexity. This article demonstrates the use of the proposed framework to develop specific SAA effectiveness standards based on UAS weight and airspace class combinations.

Feedback Model of Air Transportation System Change: Implementation Challenges for Aviation Information Systems

The U.S. air transportation system faces substantial challenges in implementing new aviation information systems to meet future demand. These challenges need to be understood and addressed in order to successfully meet future system needs. This paper uses a feedback model to describe the processes by which system change occurs. In addition, key issues in the dynamics of system change, with particular emphasis on stakeholder cost-benefit dynamics, and safety approval processes are identified. Overcoming stakeholder barriers and ensuring efficient safety approval and certification process are key enablers to the successful implementation of aviation information systems into the air transportation system. The implementation of automatic dependent surveillance-broadcast and integration of unmanned aircraft systems into the air transportation system are discussed as examples of current technology-dependent system changes.

A Survey of UAS Technologies for Command, Control, and Communication (C3)

The integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS) presents many challenges including airworthiness certification. As an alternative to the time consuming process of modifying the Federal Aviation Regulations (FARs), guidance materials may be generated that apply existing airworthiness regulations toward UAS. This paper discusses research to assist in the development of such guidance material. The results of a technology survey of command, control, and communication (C3) technologies for UAS are presented. Technologies supporting both line-of-sight and beyond line-of-sight UAS operations are examined. For each, data link technologies, flight control, and air traffic control (ATC) coordination are considered. Existing protocols and standards for UAS and aircraft communication technologies are discussed. Finally, future work toward developing the guidance material is discussed.