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All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

UAS Air Traffic Controller Acceptability Study: Evaluating Detect and Avoid Technology and Communication Delays in Simulation - 2

This study evaluated the effects of communications delays and winds on air traffic controller ratings of acceptability of horizontal miss distances (HMDs) for encounters between Unmanned Aircraft Systems (UAS) and manned aircraft in a simulation of the Dallas-Ft. Worth (DFW) airspace. Fourteen encounters per hour were staged in the presence of moderate background traffic. Seven recently retired controllers with experience at DFW served as subjects. Guidance provided to the UAS pilots for maintaining a given HMD was provided by information from Detect and Avoid (DAA) self-separation algorithms (Stratway+) displayed on the Multi-Aircraft Control System. This guidance consisted of amber "bands" on the heading scale of the UAS navigation display indicating headings that would result in a loss of well clear between the UAS and nearby traffic. Winds tested were successfully handled by the DAA algorithms and did not affect the controller acceptability ratings of the HMDs. Voice communications delays for the UAS were also tested and included one-way delay times of 0, 400, 1200, and 1800 msec. For longer communications delays, there were changes in strategy and communications flow that were observed and reported by the controllers. The aim of this work is to provide useful information for guiding future rules and regulations applicable to flying UAS in the NAS. Information from this study will also be of value to the Radio Technical Commission for Aeronautics (RTCA) Special Committee 228 - Minimum Performance Standards for UAS.

Comstock, James R., Jr.↗
NASA NTRS2016

Safety and Certification Considerations for Expanding the Use of UAS in Precision Agriculture

The agricultural community is actively engaged in adopting new technologies such as unmanned aircraft systems (UAS) to help assess the condition of crops and develop appropriate treatment plans. In the United States, agricultural use of UAS has largely been limited to small UAS, generally weighing less than 55 lb and operating within the line of sight of a remote pilot. A variety of small UAS are being used to monitor and map crops, while only a few are being used to apply agricultural inputs based on the results of remote sensing. Larger UAS with substantial payload capacity could provide an option for site-specific application of agricultural inputs in a timely fashion, without substantive damage to the crops or soil. A recent study by the National Aeronautics and Space Administration (NASA) investigated certification requirements needed to enable the use of larger UAS to support the precision agriculture industry. This paper provides a brief introduction to aircraft certification relevant to agricultural UAS, an overview of and results from the NASA study, and a discussion of how those results might affect the precision agriculture community. Specific topics of interest include business model considerations for unmanned aerial applicators and a comparison with current means of variable rate application. The intent of the paper is to inform the precision agriculture community of evolving technologies that will enable broader use of unmanned vehicles to reduce costs, reduce environmental impacts, and enhance yield, especially for specialty crops that are grown on small to medium size farms.

Hayhurst, Kelly J.↗
NASA NTRS2017

Requirements for an Integrated UAS CNS Architecture

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is investigating revolutionary and advanced universal, reliable, always available, cyber secure and affordable Communication, Navigation, Surveillance (CNS) options for all altitudes of UAS operations. In Spring 2015, NASA issued a Call for Proposals under NASA Research Announcements (NRA) NNH15ZEA001N, Amendment 7 Subtopic 2.4. Boeing was selected to conduct a study with the objective to determine the most promising candidate technologies for Unmanned Air Systems (UAS) air-to-air and air-to-ground data exchange and analyze their suitability in a post-NextGen NAS environment. The overall objectives are to develop UAS CNS requirements and then develop architectures that satisfy the requirements for UAS in both controlled and uncontrolled air space. This contract is funded under NASAs Aeronautics Research Mission Directorates (ARMD) Aviation Operations and Safety Program (AOSP) Safe Autonomous Systems Operations (SASO) project and proposes technologies for the Unmanned Air Systems Traffic Management (UTM) service. Communications, Navigation and Surveillance (CNS) requirements must be developed in order to establish a CNS architecture supporting Unmanned Air Systems integration in the National Air Space (UAS in the NAS). These requirements must address cybersecurity, future communications, satellite-based navigation APNT, and scalable surveillance and situational awareness. CNS integration, consolidation and miniaturization requirements are also important to support the explosive growth in small UAS deployment. Air Traffic Management (ATM) must also be accommodated to support critical Command and Control (C2) for Air Traffic Controllers (ATC). This document therefore presents UAS CNS requirements that will guide the architecture.

Templin, Fred↗
NASA NTRS2018

Phased Array Antenna for the Mitigation of UAS Interference

The growing demand for Unmanned Aerial Systems (UAS) operating beyond the line of sight (BLOS) has resulted in an increased interest in using existing commercial satellite communication capabilities for UAS command and control (C2) communications. The World Radiocommunication Conference in 2015 designated portions of Ku-Band and Ka-Band fixed satellite service (FSS) spectrum to support UAS C2 communications, provided that potential interference with existing co-allocated users in these bands is addressed. As the user base in this new spectrum allocation expands, there is an increased potential for interference with existing terrestrial communication systems operating under fixed service (FS) allocations. The portion of Ka-Band spectrum allocated for UAS C2 avoids significant interference issues, but the Ku-Band allocation contains a co-primary FS allocation, creating potential interference problems. Therefore, UAS must identify solutions to avoid interfering with these existing FS ground sites while maintaining good links with satellite constellations. UAS operating with conventional fixed feed parabolic antennas will have difficulty in meeting interference thresholds, especially at high latitudes where the antennas will operate with low elevation angles. As a means of addressing this limitation, NASA is investigating the use of a phased array antenna to enable mitigation of interference into ground-based FS receivers. In this paper, a novel lightweight conformal phased array antenna will be presented that can use null-steering and/or beam shaping to avoid ground interference while simultaneously providing strong satellite microwave links for communications. The reduced weight of this design and ability to integrate into the fuselage of smaller UAS platforms will also be discussed as a potential solution to provide BLOS operation via spectrum sharing for an expanding user base. This presentation will review design aspects of the conformal phased array antenna, describe the intended benefits in reducing interference with FS ground stations, and describe phased array development and test plans.

Conformal Phased Array↗
NASA NTRS2017

NASA Experience with Large and Small UAS for Atmospheric Science

NASA's unmanned aerial systems (UAS) have been utilized in many science missions, going all the way back to 1993. Some of these missions have targeted imagery (fire, vegetation) and surface measurements, but many have been applied to atmospheric research, both physical (dynamics, weather, etc.) and chemical (e.g.,composition). NASA's largest UAS, the Global Hawk, has been used to study atmospheric composition at the tropical tropopause in the Airborne Tropical TRopopause EXperiment (ATTREX) mission, where the benefit of the UAS was long range and especially duration of up to 24 hours. Two Global Hawks were used in the Hurricane and Severe Storm Sentinal (HS3) mission to observe hurricane development. Again, long duration at altitude was the significant feature of the UAS. At the smallest scale, NASA has flown DragonEye UAS to measure volcanic gas emissions in both Costa Rica and Hawaii. The small DragonEye could sample gases in hazardous locations where manned aircraft could not fly. At mid-size, the NASA SIERRA UAS has flown imaging payloads and chemical remote sensing instruments in local and international settings. Theseexperiences provide direction for best use of UAS in atmospheric science, which will be presented.

Schoenung, Susan↗
NASA NTRS2015

Enabling Earth Science Measurements with NASA UAS Capabilites

NASA's Airborne Science Program (ASP) maintains a fleet of manned and unmanned aircraft for Earth Science measurements and observations. The unmanned aircraft systems (UAS) range in size from very large (Global Hawks) to medium (SIERRA, Viking) and relatively small (DragonEye). UAS fly from very low (boundary layer) to very high altitude (stratosphere). NASA also supports science and applied science projects using UAS operated by outside companies or agencies. The aircraft and accompanying data and support systems have been used in numerous investigations. For example, Global Hawks have been used to study both hurricanes and atmospheric composition. SIERRA has been used to study ice, earthquake faults, and coral reefs. DragonEye is being used to measure volcanic emissions. As a foundation for NASA's UAS work, Altair and Ikkana not only flew wildfires in the Western US, but also provided major programs for the development of real-time data download and processing capabilities. In early 2014, an advanced L-band Synthetic Aperture Radar (SAR) also flew for the first time on Global Hawk, proving the utility of UAVSAR, which has been flying successfully on a manned aircraft. In this paper, we focus on two topics: 1) the results of a NASA program called UAS-Enabled Earth Science, in which three different science teams flew (at least) two different UAS to demonstrate platform performance, airspace integration, sensor performance, and applied science results from the data collected; 2) recent accomplishments with the high altitude, long-duration Global Hawks, especially measurements from several payload suites consisting of multiple instruments. The latest upgrades to data processing, communications, tracking and flight planning systems will also be described.

Earth Science↗
NASA NTRS2017

UAS Well Clear Recovery Against Non-Cooperative Intruders Using Vertical Maneuvers

This paper documents a study that drove the development of a mathematical expression in the detect-and-avoid (DAA) minimum operational performance standards (MOPS) for unmanned aircraft systems (UAS). This equation describes the conditions under which vertical maneuver guidance should be provided during recovery of DAA well clear separation with a non-cooperative VFR aircraft. Although the original hypothesis was that vertical maneuvers for DAA well clear recovery should only be offered when sensor vertical rate errors are small, this paper suggests that UAS climb and descent performance should be considered-in addition to sensor errors for vertical position and vertical rate-when determining whether to offer vertical guidance. A fast-time simulation study involving 108,000 encounters between a UAS and a non-cooperative visual-flight-rules aircraft was conducted. Results are presented showing that, when vertical maneuver guidance for DAA well clear recovery was suppressed, the minimum vertical separation increased by roughly 50 feet (or horizontal separation by 500 to 800 feet). However, the percentage of encounters that had a risk of collision when performing vertical well clear recovery maneuvers was reduced as UAS vertical rate performance increased and sensor vertical rate errors decreased. A class of encounter is identified for which vertical-rate error had a large effect on the efficacy of horizontal maneuvers due to the difficulty of making the correct left/right turn decision: crossing conflict with intruder changing altitude. Overall, these results support logic that would allow vertical maneuvers when UAS vertical performance is sufficient to avoid the intruder, based on the intruder's estimated vertical position and vertical rate, as well as the vertical rate error of the UAS' sensor.

UAS in the NAS↗
NASA NTRS2019

Detect-and-Avoid Alerting Performance for High-Speed UAS and Non-Cooperative Aircraft

This paper presents a set of experiments designed to assess the viability of using a smaller Detect and Avoid (DAA) volume for large Unmanned Aircraft Systems (UAS) when they are trying to remain well clear of non-cooperative visual flight rules (VFR) aircraft, in compliance with Federal regulations. The current DAA volume was defined for both cooperative and non-cooperative VFR traffic by the work of RTCA (Radio Technical Commission for Aeronautics) Special Committee 228 in 2017, in what is referred to in this paper as the Phase 1 standards. Subsequent work by the committee has been focused on enabling operations by smaller UAS that cannot carry the heavy radars required for the Phase 1 DAA Minimum Operational Performance Standards (MOPS). The work discussed in this paper will explore whether a Phase 1 UAS using a Phase 1 radar can use the reduced non-cooperative DAA alerting volume being studied for smaller, slower Phase 2 UAS without significantly degrading system safety. The study uses UAS models and background traffic from previous Phase 1 and Phase 2 research to run an unmitigated simulation that will examine alerting performance using different DAA well clear definitions. The primary metrics are also tied to the alerting performance of the DAA system, and include average alerting times, probabilities of missed and late alerts, and the probability of a near mid-air collision given a loss of "well clear," as defined by the DAA system. Results are expected to help RTCA make the determination whether or not the DAA well clear definition for Phase 1 UAS can be reduced for non-cooperative VFR aircraft.

UAS↗
DOE OSTI2024

Case study of UAS ignition of prescribed fire in a mixedwood on the William B. Bankhead National Forest, Alabama

Abstract Background For at least four decades, practitioners have recognized advantages of aerial versus ground ignition for maximizing the effectiveness of prescribed fires. For example, larger areas can be ignited in less time, or ignition energy may be variously targeted over an area in accordance with the uneven distribution of fuels. The maturation of wireless communication, geopositioning systems, and unmanned aerial systems (UAS) has enhanced those advantages, and UAS approaches also provide further advantages relative to helicopter ignitions, such as reduced risk to human safety, lower operating costs, and higher operational flexibility. In a long running study at the Bankhead National Forest in northcentral Alabama, prescribed fire has been used for nearly 20 years. Most of the burns have been hand-ignited via drip torches, while some have been aerially ignited via helicopter. In March 2022, for the first time, a UAS was used to ignite prescribed fires across a landscape that included a long-term research stand. This field note relates comparisons of both fire behavior and fuel consumption metrics for the UAS-ignited burn versus previous burns on the same stand, and versus burns of other research stands in the same year. Results The UAS-ignited prescribed fire experienced burn effects similar to those from ground-ignited prescribed fires on the same stand in previous years, as well as those from ground-ignited prescribed fires on other stands in the same year. Conclusion This post hoc analysis suggests that UAS ignition approaches may be sufficient for achieving prescribed burn goals, thereby enabling practitioners to realize the advantages offered by that ignition mode.

Environmental Sciences & Ecology↗
DOE OSTI2023

Current UAS Capabilities for Geospatial Spectral Solutions

Unmanned aerial systems (UAS) are playing an increasingly pivotal role in advancing the remote collection of data. The various datasets collected by these cutting-edge systems provide near-real-time information and help inform end users on everything from disaster recovery efforts to monitoring atmospheric constituents. This chapter focuses on how the collection of imagery has progressed over time, including the pivotal role UAS play in building large-scale datasets driving data analysis. The authors report the findings of a 2018–2021 survey of the fields that use UAS, the UAS platforms most commonly used, and the sensor components users select to outfit their UAS. The chapter will also discuss the range of platforms currently available, with a specific focus on issues including battery life, data downlinks, data processing times, edge computing, and availability of new sensors. The authors will also discuss the future direction of UAS platforms as well as many of the problems associated with the high spatial and temporal resolution of modern geospatial datasets.

Cotten, David↗
DOE OSTI2022

UAS Live Incursion Drills Survey

Unmanned aircraft systems (UAS/drones) are rapidly evolving and are considered an emerging threat by nuclear facilities throughout the world. Due to the wide range of UAS capabilities, members of the workforce and security/response force personnel need to be prepared for a variety of drone incursion situations. Tabletop exercises are helpful, but actual live exercises are often needed to evaluate the quick chain of events that might ensue during a real drone fly-in and the essential kinds of information that will help identify the type of drone and pilot. Even with drone detection equipment, the type of UAS used for incursion drills can have a major impact on detection altitude and finding the UAS in the sky. Using a variety of UAS, the U.S. National Nuclear Security Administration (NNSA) Office of International Nuclear Security (INS) would like to offer partners the capability of adding actual UAS into workforce and response exercises to improve overall UAS awareness as well as the procedures that capture critical steps in dealing with intruding drones.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2007

NASA Dryden's UAS Service Capabilities

The vision of NASA s Dryden Flight Research Center is to "fly what others only imagine." Its mission is to advance technology and science through flight. Objectives supporting the mission include performing flight research and technology integration to revolutionize aviation and pioneer aerospace technology, validating space exploration concepts, conducting airborne remote sensing and science missions, and supporting operations of the Space Shuttle and the International Space Station. A significant focus of effort in recent years has been on Unmanned Aircraft Systems (UAS), both in support of the Airborne Science Program and as research vehicles to advance the state of the art in UAS. Additionally, the Center has used its piloted aircraft in support of UAS technology development. In order to facilitate greater access to the UAS expertise that exists at the Center, that expertise has been organized around three major capabilities. The first is access to high-altitude, long-endurance UAS. The second is the establishment of a test range for small UAS. The third is safety case assessment support.

Bauer, Jeff↗
NASA NTRS2006

HALE UAS Concept of Operations. Version 3.0

This document is a system level Concept of Operations (CONOPS) from the perspective of future High Altitude Long Endurance (HALE) Unmanned Aircraft Systems (UAS) service providers and National Airspace System (NAS) users. It describes current systems (existing UAS), describes HALE UAS functions and operations to be performed (via sample missions), and offers insight into the user s environment (i.e., the UAS as a system of systems). It is intended to be a source document for NAS UAS operational requirements, and provides a construct for government agencies to use in guiding their regulatory decisions, architecture requirements, and investment strategies. Although it does not describe the technical capabilities of a specific HALE UAS system (which do, and will vary widely), it is intended to aid in requirements capture and to be used as input to the functional requirements and analysis process. The document provides a basis for development of functional requirements and operational guidelines to achieve unrestricted access into the NAS. This document is an FY06 update to the FY05 Access 5 Project-approved Concept of Operations document previously published in the Public Domain on the Access 5 open website. This version is recommended to be approved for public release also. The updates are a reorganization of materials from the previous version with the addition of an updated set of operational requirements, inclusion of sample mission scenarios, and identification of roles and responsibilities of interfaces within flight phases.

Source record↗
NASA NTRS2009

UAS Related Activities at NASA's Dryden Flight Research Center

NASA's Dryden Flight Research Center is completing its refurbishment and initial flights of one the pre-production Global Hawk aircraft it received from the U.S. Air Force. NASA Dryden has an agreement with the Global Hawk s manufacturer, Northrop Grumman, to partner in the refurbishment and flight operations of the vehicles. The National Oceanic and Atmospheric Administration (NOAA) has also partnered on the project and is assisting NASA with project management and pilot responsibilities for the aircraft. NASA and NOAA will be using the Global Hawks to conduct earth science research. The earth science community is increasing utilizing UAS of all sizes and capabilities to collect important data on a variety of issues including important global climate change issues. To pursue the data collection needs of the science community there is a growing demand for international collaboration with respect to operating UAS in global airspace. Operations of NASA s Ikhana aircraft continued this past year. The Ikhana is a modified Predator B UAS. A UAS dedicated to research at NASA Dryden is the X-48B blended wing body research aircraft. Flight tests with the 500- pound, remotely piloted test vehicle are now in a block 4 phase involving parameter identification and maneuvers to research the limits of the engine in stall situations. NASA s participation in the blended wing body research effort is focused on fundamental, advanced flight dynamics and structural design concepts within the Subsonic Fixed Wing project, part of the Fundamental Aeronautics program managed through NASA s Aeronautics Research Mission Directorate. Potential benefits of the aircraft include increased volume for carrying capacity, efficient aerodynamics for reduced fuel burn and possibly significant reductions in noise due to propulsion integration options. NASA Dryden continues to support the UAS industry by facilitating access to three specially designated test areas on Edwards Air Force Base for the development of small UAS.

Bauer, Jeffrey E.↗
NASA NTRS2010

Modeling and Simulation of an UAS Collision Avoidance Systems

This paper describes a Modeling and Simulation of an Unmanned Aircraft Systems (UAS) Collision Avoidance System, capable of representing different types of scenarios for UAS collision avoidance. Commercial and military piloted aircraft currently utilize various systems for collision avoidance such as Traffic Alert and Collision A voidance System (TCAS), Automatic Dependent Surveillance-Broadcast (ADS-B), Radar and ElectroOptical and Infrared Sensors (EO-IR). The integration of information from these systems is done by the pilot in the aircraft to determine the best course of action. In order to operate optimally in the National Airspace System (NAS) UAS have to work in a similar or equivalent manner to a piloted aircraft by applying the principle of "detect-see and avoid" (DSA) to other air traffic. Hence, we have taken these existing sensor technologies into consideration in order to meet the challenge of researching the modeling and simulation of an approximated DSA system. A Schematic Model for a UAS Collision Avoidance System (CAS) has been developed ina closed loop block diagram for that purpose. We have found that the most suitable software to carry out this task is the Satellite Tool Kit (STK) from Analytical Graphics Inc. (AGI). We have used the Aircraft Mission Modeler (AMM) for modeling and simulation of a scenario where a UAS is placed on a possible collision path with an initial intruder and then with a second intruder, but is able to avoid them by executing a right tum maneuver and then climbing. Radars have also been modeled with specific characteristics for the UAS and both intruders. The software provides analytical, graphical user interfaces and data controlling tools which allow the operator to simulate different conditions. Extensive simulations have been carried out which returned excellent results.

Oliveros, Edgardo V.↗
NASA NTRS2011

UAS Modeling of the Communication Links Study Results

There were many links calculated for this and the other scenarios. The rain was analyzed for 99.9% availability with rain rated of none, 20 mm/hr and 90 mm/hr at a height of 5 km out to 25 NM. This was done for each scenario for LOS and for BLOS links for Scenario 5 and 6. Scenario 1 was a LOS-only scenario. Use of two 3 dB Antennas on both ends. The CS2 was unable to maintain a control RF Link during the flight. The largest access gap periods between object top and bottom UA antennae were caused by terrain (ridges and hills). The CS Antenna was changed to High Gain Directional Antenna, all three CS maintained lock on vehicle. There were RF dropouts between the top and bottom UA antennae caused by aircraft obstructions (fuselage, wings, wheel assembles, etc.). Note that for this study antenna locations were placed on top and bottom center of the UA body. Future study should include actual UA antenna locations on the aircraft providing manufactures are willing to provide information. The importance of CS location(s) was demonstrated for primary or backup CS. With a second backup CS placed in a suitable location the UA was able to maintain an overall RF link. The actual location of both backup CSs required the antenna location to be place 150 ft above ground in order to establish a RF link between the UA and CS.

Birr, Richard↗
NASA NTRS2012

Varying Levels of Automation on UAS Operator Responses to Traffic Resolution Advisories in Civil Airspace

Continuing demand for the use of Unmanned Aircraft Systems (UAS) has put increasing pressure on operations in civil airspace. The need to fly UAS in the National Airspace System (NAS) in order to perform missions vital to national security and defense, emergency management, and science is increasing at a rapid pace. In order to ensure safe operations in the NAS, operators of unmanned aircraft, like those of manned aircraft, may be required to maintain separation assurance and avoid loss of separation with other aircraft while performing their mission tasks. This experiment investigated the effects of varying levels of automation on UAS operator performance and workload while responding to conflict resolution instructions provided by the Tactical Collision Avoidance System II (TCAS II) during a UAS mission in high-density airspace. The purpose of this study was not to investigate the safety of using TCAS II on UAS, but rather to examine the effect of automation on the ability of operators to respond to traffic collision alerts. Six licensed pilots were recruited to act as UAS operators for this study. Operators were instructed to follow a specified mission flight path, while maintaining radio contact with Air Traffic Control and responding to TCAS II resolution advisories. Operators flew four, 45 minute, experimental missions with four different levels of automation: Manual, Knobs, Management by Exception, and Fully Automated. All missions included TCAS II Resolution Advisories (RAs) that required operator attention and rerouting. Operator compliance and reaction time to RAs was measured, and post-run NASA-TLX ratings were collected to measure workload. Results showed significantly higher compliance rates, faster responses to TCAS II alerts, as well as less preemptive operator actions when higher levels of automation are implemented. Physical and Temporal ratings of workload were significantly higher in the Manual condition than in the Management by Exception and Fully Automated conditions.

Kenny, Caitlin↗
NASA NTRS2014

UAS-Systems Integration, Validation, and Diagnostics Simulation Capability

As part of the Phase 1 efforts of NASA's UAS-in-the-NAS Project a task was initiated to explore the merits of developing a system simulation capability for UAS to address airworthiness certification requirements. The core of the capability would be a software representation of an unmanned vehicle, including all of the relevant avionics and flight control system components. The specific system elements could be replaced with hardware representations to provide Hardware-in-the-Loop (HWITL) test and evaluation capability. The UAS Systems Integration and Validation Laboratory (UAS-SIVL) was created to provide a UAS-systems integration, validation, and diagnostics hardware-in-the-loop simulation capability. This paper discusses how SIVL provides a robust and flexible simulation framework that permits the study of failure modes, effects, propagation paths, criticality, and mitigation strategies to help develop safety, reliability, and design data that can assist with the development of certification standards, means of compliance, and design best practices for civil UAS.

Buttrill, Catherine W.↗