experimental flight testing for assessing the safety of ... · corridors, dynamic geo-fencing,...

American Institute of Aeronautics and Astronautics

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Experimental Flight Testing for Assessing the Safety of Unmanned Aircraft System Safety-Critical Operations

Christine M. Belcastro1 NASA Langley Research Center

Hampton, Virginia 23681

David H. Klyde2 Systems Technology, Inc.

Hawthorne, California 90250

Michael J. Logan 3 NASA Langley Research Center


Richard L. Newman4

Crew Systems Seattle, Washington, 98165

John V. Foster 5 NASA Langley Research Center


Many beneficial civilian applications of commercial and public small unmanned aircraft systems (sUAS) in low-altitude uncontrolled airspace have been proposed and are being developed. Associated with the proliferation of civil applications for sUAS is an expected requirement for BVLOS (beyond visual line of sight) operations with increasing use of autonomous systems and operations under increasing levels of urban development and airspace usage. It is also anticipated that future demand will necessitate a shift toward multi-UAS operations in which a single operator will be responsible for the safe operation of multiple sUAS simultaneously. As risk increases for ensuring the safety of manned aircraft and persons on the ground (e.g., in suburban and urban environments), these operations become safety-critical. Ensuring the safety and effectiveness of these safety-critical operations will require an assessment of the impacts of safety hazards on sUAS and their operation, as well as the development of hazard mitigation and contingency management systems and strategies that reduce the associated risk. Safety assessments must be performed under nominal and off-nominal conditions using analysis, simulation, and experimental testing that utilize a set of test scenarios designed to expose safety vulnerabilities. Moreover, the effectiveness of hazard mitigation systems and contingency management strategies must be similarly evaluated. Experimental test techniques and hazards-based test scenarios that facilitate these safety assessments are therefore needed, as well as sUAS computer simulation models that are capable of characterizing off-nominal vehicle dynamics. Ultimately, real-time risk assessment and safety assurance systems may be needed for safety-critical operations such that determination of unacceptable risk will initiate hazard mitigation actions to reduce risk to an acceptable level and thereby ensure safety. This capability may especially be needed to enable (and ensure) safe multi-UAS operations under uncertain, off-nominal, and hazardous conditions. This will require the development of methodologies for the effective detection and mitigation of emergent (unanticipated) safety hazards, as well as human-automation interface systems that enable effective teaming under adverse conditions. Validation of these systems will require (in part) experimental testing in a realistic and relevant flight environment. This paper presents experimental flight test techniques and an initial set of hazards-based test scenarios that are under development for assessing the safety of sUAS operations. Key research and technical requirements for establishing a flight test environment for assessing the safety of multi-UAS operations are also briefly addressed.

1 Senior Research Engineer, Dynamic Systems and Control Branch, MS 308, E-Mail: [email protected]; AIAA

Associate Fellow. 2 Technical Director, E-Mail: [email protected]; AIAA Associate Fellow. 3 Senior Engineer, Aeronautics Systems Engineering Branch, MS 238, E-Mail: [email protected]; AIAA member. 4 Retired, FAA, Post Office Box 25054, E-Mail: [email protected]; AIAA Associate Fellow. 5 Senior Research Engineer, Flight Dynamics Branch, MS 308, E-Mail: [email protected]; AIAA Associate Fellow.

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17th AIAA Aviation Technology, Integration, and Operations Conference

5-9 June 2017, Denver, Colorado

AIAA 2017-3274

This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

AIAA AVIATION Forum

http://crossmark.crossref.org/dialog/?doi=10.2514%2F6.2017-3274&domain=pdf&date_stamp=2017-06-05


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Nomenclature

AirSTAR = airborne subscale transport aircraft research BRS = base research station BVLOS = beyond visual line of sight FW = fixed wing sUAS configuration GPS = global positioning system LOC = loss of control MOS = mobile operations station MR = multirotor sUAS configuration MTE = mission task element sUAS = small unmanned aircraft system UAS = unmanned aircraft system UH = unmanned helicopter sUAS configuration UTM = UAS traffic management VLOS = within visual line of sight V&V = validation and verification

I. Introduction

ANY beneficial civilian applications of commercial and public small unmanned aircraft systems (sUAS) in low-altitude uncontrolled airspace have been proposed and are being developed. These applications include

delivery of goods, infrastructure monitoring, precision agriculture, search and rescue, and many others. 1 Figure 1 provides a graphical depiction of sUAS low-altitude operations.

Figure 1. Depiction of sUAS Operations in Low-Altitude Airspace

These UAS operations will increasingly require interactions with an array of existing users of that airspace -

general aviation aircraft, helicopters, gliders, balloons, and even parachutists. However, the safety of these existing

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operations cannot be compromised by the introduction of the new UAS operations. Currently, there is no automation infrastructure to accommodate the widespread use of UAS operations in uncontrolled airspace. The NASA Unmanned Aircraft System (UAS) Traffic Management (UTM) Project2 seeks to facilitate the safe use of low-altitude airspace (below 500 feet) by operators of small UAS (sUAS of 55 lbs or less) for a wide variety of applications. The UTM system will enable safe and efficient low-altitude airspace operations by providing services such as airspace design, corridors, dynamic geo-fencing, severe weather and wind avoidance, congestion management, terrain avoidance, route planning, re-routing, separation management, sequencing, spacing, and contingency management. UTM is essential to enable the accelerated development and use of civilian sUAS applications. In its most mature form, the UTM system will be developed using autonomicity characteristics, which will include self-configuration, self-optimization and self-protection. Associated with the proliferation of civil applications for sUAS is a paradigm shift from single-UAS remotely piloted within visual line of sight (VLOS) operations in remote locations to multi-UAS beyond visual line of sight (BVLOS) operations with increasing use of autonomous systems and operations under increasing levels of urban development and airspace usage. It is also anticipated that future demand will necessitate a shift toward multi-UAS operations in which a single operator will be responsible for the safe operation of multiple sUAS simultaneously. Along with increasing levels of operational complexity and sophistication come increasing complexity of hazards sources and their levels of safety / risk impacts. 3, 4 As risk increases for ensuring the safety of manned aircraft and persons on the ground (e.g., in suburban and urban environments), these operations become safety-critical. Ensuring the safety and effectiveness of these safety-critical operations will require an assessment of the impacts of safety hazards on sUAS and their operation, as well as the development of hazard mitigation and contingency management systems5, 6, 7, 8, 9, 10, 11, 12, 13 and strategies that reduce the associated risk. Safety assessments must be performed under nominal and off-nominal conditions using analysis, simulation, and experimental testing that utilize a set of test scenarios designed to expose safety vulnerabilities. Moreover, the effectiveness of hazard mitigation systems and contingency management strategies must be similarly evaluated. Experimental test techniques and hazards-based test scenarios that facilitate these safety assessments are therefore needed, as well as sUAS computer simulation models that are capable of characterizing off-nominal vehicle dynamics.14 ,15, 16 Ultimately, real-time risk assessment17 and safety assurance systems may be needed for safety-critical operations such that determination of unacceptable risk will initiate hazard mitigation actions to reduce risk to an acceptable level and thereby ensure safety. This capability may especially be needed to enable (and ensure) safe multi-UAS operations under uncertain, off-nominal, and hazardous conditions. This will require the development of methodologies for the effective detection and mitigation of emergent (unanticipated) safety hazards, as well as human-automation interface systems that enable effective teaming under adverse conditions. Validation of these systems will require (in part) experimental testing in a realistic and relevant flight environment. This paper presents experimental test techniques and an initial set of hazards-based test scenarios that are under development for assessing the safety of sUAS operations. Experimental testing for assessing the effectiveness of real-time risk assessment and safety assurance systems for multi-UAS operations is also briefly discussed. The paper is organized as follows: Section II summarizes experimental test techniques and some recent flight test results for assessing safety under off-nominal conditions; Section III summarizes the approach being taken for developing test scenarios and an initial set of test scenarios developed using this approach; Section IV discusses considerations for establishing a multi-UAS flight test environment for assessing the safety of sUAS operations; and Section V provides a summary of the paper and some concluding remarks. Supplemental information to these sections is provided in the Appendices.

II. Experimental Flight Testing for Safety Assessment of sUAS under Off-Nominal Conditions The operation of sUAS within the UTM system is expected to migrate toward high-risk environments associated

with suburban and urban settings. It is therefore vital that off-nominal events and their safety impacts for sUAS operations within the UTM system are assessed so that they can be effectively mitigated. This assessment is being accomplished through the development of enhanced simulations for characterizing sUAS dynamics and control characteristics under off-nominal conditions, as well as through the development and implementation of flight test techniques for assessing safety under off-nominal conditions. This section summarizes flight test capabilities and recent results for performing safety assessments of sUAS operating under off-nominal conditions.

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A. Motivation and Research Requirements

Flight testing is required to support the safety assessments being performed for sUAS operations. A key aspect of this testing is the assessment of sUAS dynamics and control characteristics under off-nominal conditions (e.g., system failures). This is the focus of the flight test work presented in this paper. These flight test results will be used in validating vehicle simulation models being developed (see Ref. [16]) for characterizing off-nominal condition effects. Other testing will focus on evaluating the effectiveness of hazard mitigation systems at the vehicle level and contingency management systems and strategies at the operational level. Flight testing will also be used in assessing the effectiveness of real-time risk assessment (see Ref. [17]) and safety assurance systems. Ultimately, a multi-UAS flight test environment will be established for developing and validating safety requirements for multi-UAS operations (see Section IV). The remainder of this section focuses on flight testing of sUAS under system failures.

B. Flight Test Approach, Failure Emulation, and Initial Flight Test Results 1. Flight Test Approach

A series of flight tests were developed to assess failure responses in three different platforms, two multi-rotors and one fixed-wing. For the multi-rotors, two likely failure scenarios were developed, one where a motor fails or degrades while the vehicle is in a stable hover and the other where a motor fails or degrades while the vehicle is navigating a waypoint pattern. For the fixed-wing platform, scenarios were developed that emulated control surface failures of neutral, positive and negative deflections. Additionally, the on-board GPS would be selectively disabled during a waypoint following function. All three platforms used the Pixhawk autopilot as being representative of the types of autopilots currently being used by industry.

Figure 2 shows one of the multi-rotors referred to as “Y-6-2”. It is a 3-arm configuration with motors on both the top and bottom of each arm. The motor selected for “failure” was the top right motor.

Figure 2. Y-6-2 sUAS Configuration

Figure 3 shows the second multi-rotor, a Tarot X6, used in the experiments. The motor selected for the “failure” was the right center motor. The vehicle also had a video camera and transmitter which was downlinked to the ground control station (GCS).

Figure 3. Tarot X6 sUAS

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The fixed-wing sUAS is shown in Figure 4. It is a former U.S. Army target drone converted to have an autopilot, landing gear, and back-pointing camera to obtain visual control surface deflections. A multiplexer was installed which allowed for selection of the control surface failure setting via the radio control transmitter. In addition, a GPS power relay was installed to enable the ability to cut power to the GPS module, observe the response, and restore power to the GPS.

Figure 4. Modified FQM-117B named MigLH

2. Failure Emulation

In order to obtain realistic failure results, sUAS platforms were modified to allow for emulating a failure under controlled conditions. For multi-rotor sUAS, provisions were made to be able to switch the throttle signal going to one of the rotor motor controllers to a value selectable by the radio-control transmitter. This allowed for the test to implement both a complete failure of a rotor emulating loss of motor controller, motor failure, or prop failure, and a “partial” failure emulating a control signal issue where the control signal pulse width modulation to the motor controller is frozen via a “hold last valid setting” by the motor controller. In the case of fixed-wing sUAS, provisions were made to be able to fail control surfaces (e.g., right aileron, right side elevator, and rudder) at selectable positions to emulate a servo failure or a mechanically jammed control surface. In addition, the fixed-wing vehicle was outfitted to incorporate the ability to selectively disable the on-board GPS.

3. Flight Test Activities and Current Status

Flight experiments were defined with the multi-rotors for failing a motor in both fixed, stable hover and waypoint navigation modes. In these tests, the throttle settings included nominal hover, +/-25%, +/-50%, -75%, and -100% (i.e., full off). Note that during testing, it was determined for both types of multi-rotors that a +50% throttle setting or above was unrecoverable in hover. The initial flight test plan involving the aircraft of Section II.B.1 and the failure emulation method of Section II.B.2 is provided in Table 1. These flight tests were conducted in April 2017.

Table 1. Initial Flight Test Plan.

Flight Experiment Schedule

Dates: 4/12/2017-4/21/2017

Flt # Vehicle Total Time Mode Fail setting Status

1 Y-6-2 9 Loiter Nominal Completed

Nominal - 25% Completed

Nominal + 25% Completed




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Nominal + 75%* Not Flown



2 Y-6-2 10 Auto Nominal Completed



3 Y-6-2 10 Auto Nominal - 75% Completed



4 Tarot X6 9 Loiter Nominal Completed









5 Tarot X6 10 Auto Nominal Completed



6 Tarot X6 10 Auto Nominal - 75% Completed


Nominal + 25% Not flown

7 MigLH 12 Auto Check Flight Check Flight

8 MigLH 12 Auto Aileron fail - neutral Completed

Aileron fail +25% Completed

Aileron fail -25% Completed



10 MigLH 12 Auto Rud fail - neutral Completed

Rud fail +25% Completed



11 MigLH 12 Auto Elev fail - neutral Completed

Elev fail -25% Completed

Elev fail +25% Completed

Elev fail -50% Not flown

Elev fail +50% Completed

12 MigLH 10 Auto GPS power fail Completed

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Failure durations ranged from 1 – 30 seconds, depending on the effect, with longer durations applied to the fixed wing sUAS. That is, if the failure did not cause visible distress to the component or the vehicle it was allowed to persist for several seconds. If the failure effect was visibly significant or destabilizing, the failure was reversed more quickly to prevent entry into an unrecoverable state.

The preliminary results of the flight experiments performed to date have illustrated important characteristics. The multi-rotors were generally able to ignore a nominal hover throttle setting “failure” in hover. However, even this benign condition made navigating a waypoint pattern problematic. Neither multi-rotor was able to recover from a +50% or higher “stuck” throttle setting. Figure 5 shows the Tarot X-6 with its right center motor in the “failed” condition of complete shutdown in hover.

Figure 5. Tarot X6 in Hover with Right Center Motor Shut Down

In some cases, both multi-rotors were unable to hold a single fixed position but would instead fly a very tight circle around the hover position. In addition, both vehicles would exhibit a fairly dynamic response to a complete shutdown of one rotor. Figure 6 shows the trigger plot and the pitch and roll response of the Y-6-2. As can be seen, the pitch and roll extent is quite dramatic. The Tarot X6 had slightly lower excursions than the Y-6-2.

Figure 6. Trigger Plot and Roll/Pitch Attitude (Degrees) Plot of Y-6-2 with Emulated Rotor Failure

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The fixed-wing sUAS was not affected by a frozen-neutral aileron setting. Waypoint navigation with the right

aileron fixed was indistinguishable from nominal flight path. The ± 25% failures showed a slight deviation from the assigned flight path but were generally able to turn the waypoint “corners” in the box pattern.

Additional testing with larger off-nominal settings indicated that if the failed aileron is stuck to either +/- 100%, as would be the case with a jam, the vehicle can barely maneuver around the waypoint pattern. As would be expected, the remaining operational aileron is deflected in fully the opposite direction leaving only the rudder to effect a turn.

Testing a rudder failure on the fixed-wing vehicle was conducted as well. The patterns in Figure 7 were re-used with the waypoints arranged in a clockwise fashion to necessitate a right turn at the corners. A neutral rudder failure had little impact on the ground track. However, a full left rudder deflection made making a right turn difficult. Conversely, having a full right rudder failure made the ground track appear nominal with turns taking a normal amount of time and cross-track error.

Figure 7. MigLH Waypoint Navigation with Neutral, +25%, and -25% Aileron Failure

The elevator testing was similarly selected to represent half the elevator failed in a specific deflection between -

100% and +100%. When the half elevator was failed full down, the vehicle made an abrupt dive and did not appear to recover above the safety floor altitude. When the half elevator was failed full up, the vehicle began to climb but the throttle power was cut, the airspeed decayed rapidly, and the other half elevator was deflected full down. Eventually, the vehicle leveled off but was unable to navigate the waypoint pattern with the compromised elevator.

When the GPS power was turned off, the ability of the vehicle to maintain altitude, course, and attitude degraded very rapidly. Part of this was due to the compass, packaged with the GPS unit, deriving its power from the GPS power lead rather than the Inter-Integrated Circuit (I2C) bus to which it is connected. Figure 8 shows that when the GPS status goes to zero (i.e., failed, depicted by the red trace), the vehicle began a distinct nose-dive until the safety pilot unfailed the GPS and took control of the vehicle (depicted by the green trace).

Figure 8. GPS Failure and Pitch Attitude (Degrees) Plots for Fixed-Wing MigLH Platform

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C. Next Steps and Future Directions

A number of future tests are envisioned to make the data set more comprehensive. Some of these include testing more vehicle types, such as an octocopter and a different fixed-wing sUAS. Tests are also planned to evaluate the ability of multi-rotor sUASs to descend in the presence of failure and to navigate when the GPS system has failed. Different types of autopilots will also be tested to determine whether the phenomenon captured during these tests is autopilot specific.

Other planned flight test activities will support the sUAS dynamics modeling research for off-nominal conditions, as well as the evaluation of hazard mitigation systems. The evaluation of hazard mitigation systems will include support in the development of a comprehensive set of test scenarios, as described in Section III, including the validation of performance requirements.

A potential outcome of this work is the development of safety recommendations and recommended “best practices” for improving the robustness of both the hardware platform and the airborne software, as well as for developing and evaluating resilient systems for off-nominal conditions. These recommendations would allow system designers to develop safer, more reliable vehicles even in the event of component failures, which will be mandatory on future sUAS that operate BVLOS and under high-risk safety-critical conditions.

III. Preliminary Hazards-Based Test Scenarios for Safety Assessment of sUAS The operation of sUAS in high-risk environments (e.g., suburban, urban, and congested population densities) will

require the development and implementation of hazards mitigation systems and contingency management strategies for reducing risk. Implementing these systems and strategies for safety-critical applications will necessitate a thorough evaluation of their effectiveness and clear identification of any limitations. Such evaluations will require the development and application of a realistic set of hazards-based test scenarios. This section summarizes a proposed approach for the development of hazards-based test scenarios for sUAS and presents an initial set of test scenarios developed for a selected hazard. The scenarios are based on mission task elements (MTEs) and include nominal and off-nominal conditions. Nominal test scenarios are developed to establish a baseline for assessing performance. Section III.A describes the technical approach, Section III.B presents an initial set of nominal test scenarios, and Section III.C presents an initial set of hazards-based test scenarios.

A. Technical Approach: Use of Mission Task Elements

This section describes the use of mission task elements (MTEs) in the development of sUAS test scenarios for nominal and off-nominal conditions.

1. A Formal Approach Lessons learned from the world of manned flight handling qualities has been used to establish test scenarios for

sUAS. The first lesson is that flight test is the ultimate verification of handling qualities and successful flight verification can only be made using well defined evaluation tasks. The aeronautical design standard that defines handling qualities requirements for military rotorcraft, ADS-33E-PRF18, provides the most successful use of well-defined evaluation tasks. The approach used in this design standard is referred to as a mission-oriented approach. In a mission-oriented approach to aircraft handling qualities19, the aircraft mission is broken down into realistic mission task elements (MTEs). Specific flight test demonstration maneuvers are then defined for each MTE. For example, the mission of a commercial transport is to deliver cargo and passengers from a departure location to an arrival location. This mission can then be broken down into smaller elements, mission task elements, that include takeoff/departure climb, cruise, descent, loiter, approach, and landing. Other MTEs may include less frequent events such as a missed approach/go-around.

Ultimately, a truly mission-oriented approach will have all quantitative requirements tied directly to realistic MTEs, and for every MTE, there will be a corresponding demonstration maneuver. The requirements define what is expected of the airplane, while the demonstration maneuvers provide an explicit way of verifying handling qualities in flight. Traditionally, the flight evaluations are conducted with test pilots that are trained to provide these assessments using formal rating procedures20. Such an approach is not recommended here for sUAS hazard

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assessment, since most future use cases will involve autonomous vehicle operations. Instead, sUAS performance will be quantified via a direct comparison of MTE performance under nominal conditions with the MTE performance observed under selected hazard scenarios. Thus, the MTE process can be applied as a means to define baseline vehicle performance from which the performance in a given hazard scenario can then be compared and quantified.

2. MTEs and Hazard Scenario Testing

How does the MTE approach apply to sUAS? As described in this paper and elsewhere (see Refs. [3], [4], [16], and [17]), there are numerous use cases that are emerging for sUAS as access to airspace including beyond visual line of sight operations is granted. These use cases define missions that can be broken down into smaller elements – MTEs. The approach is therefore to formally define MTEs for current and anticipated use cases with specific, but realistic performance requirements from which the nominal vehicle performance can be defined. Scenarios can then be introduced and tested for the MTEs analytically, via computer simulation, and in flight from which the vehicle performance in the presence of a hazard can be compared with the nominal performance, thereby providing a quantifiable means to assess the impact of the given hazard. This process is illustrated in Figure 9. It should be noted that this same process can be used to assess hazard mitigation approaches.

Figure 9. Use of MTEs to Assess sUAS Hazard Scenario Performance.

B. Preliminary Nominal Test Scenarios for sUAS

This section describes the common and specialized mission task elements (MTEs) developed for sUAS by vehicle configuration and the associated test scenarios for nominal conditions. Performance and safety requirements are considered for increasing levels of population density (remote/rural, suburban, and urban/congested).

1. sUAS Use Case Summary

A large number (> 100) of sUAS use cases were obtained from industry, government, and academia to characterize future UTM operations. Details of this work were presented in Ref. [3]. These sUAS use cases were then organized into categories and used in identifying future potential hazards. These use case categories are used herein to develop mission-based test scenarios for evaluating nominal performance and the effectiveness of hazard mitigation systems developed for reducing risk. Table 2 summarizes the sUAS use case categories defined in Ref. [3].

Table 2. Summary of Use Case Categories Used in the Development of Mission-Based Test Scenarios

Use Case Category Description

Videography at Public Events Includes Sporting Events, Fireworks Displays, Parades, Festivals, etc.

Security at Public Events & Counter UAS Operations

Monitoring, Detection, & Mitigation of Security Threats & Rogue UAS

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Infrastructure Inspection Critical Infrastructure – Includes Dams, Canals, Railroads, Bridges, Mines, Power

Distribution Lines, Oil Pipelines, Onshore Oil and Gas Facilities, Offshore Oil Platforms, and Wind Turbine Blades, etc.

Search & Rescue Includes Missing Persons, Missing Airplane, Missing Ship, Survivors from a

Shipwreck or Aircraft Accident, etc.

Disaster Response Includes Widespread Events Associated with Landslides, Mudslides, Hurricanes,

Floods, Tornadoes, Earthquakes, etc., and Includes Volcano Inspection / Monitoring after Eruption Event, Avalanche Monitoring / Control, Flood Mapping, etc.

Emergency Response Includes Localized Events such as Aircraft Accidents, Multi-Vehicle Collisions, etc.

Monitoring & Patrol Includes Border Patrol, Individual / Group / Vehicle Identification and Tracking,

Maritime Patrol along Coastal Border Regions, Intelligence, Surveillance, and Reconnaissance of an Area or Building of Interest, etc.

Maritime Surveillance & Security

Includes: Surveillance, Situational Awareness, and Security of Ports, Waterways, and the Coast; Security zone enforcement (e.g., deterring unauthorized vessels from

entering a security zone); Airborne patrol of waterfront facilities (marinas, boat launch sites, etc.); Vessel inspection prior to boarding; Facility security inspections;

Airborne wide-area surveillance in ports and/or offshore for potential terrorist activity; Drug interdiction

Wildfire Monitoring & Control Includes Coordinated Multi-Vehicle (Air and Ground) Operations

Law Enforcement Includes Aerial Photography for Suspect Tracking, Motor Vehicle Accident

Response, Crime Scene Investigation, Accident Scene Investigation, Search and Rescue of Missing Persons [Amber Alerts, ...], etc.

Package / Cargo Delivery Includes Package Delivery to Individual Consumers in Rural / Suburban / Urban Environment, and Delivery of Emergency Medical Supplies in Remote Locations

Imaging / Data Acquisition / Survey of Public / Private Land

Includes Construction Site Inspection, Terrain Mapping, Land Surveys for Future Construction, etc.

Environmental and Wildlife Monitoring & Protection

Includes Wildlife Inventory and Monitoring, Atmosphere / Environment Data Collection and Monitoring, Air and Water Quality/Pollution Monitoring, Climate Change Analysis, Volcano Inspection / Monitoring, Landscape Monitoring, etc.

Precision Agriculture Includes Crop Dusting, Inspection, Vegetation Inventory and Monitoring, etc.

2. Mission Task Element Descriptions

Building upon the MTE definition process established in the handling qualities discipline, the MTEs will be defined using the formal description process outlined in a previous work 21, 22. It is important that the MTEs be carefully defined to ensure repeatability within a given assessment program and between disparate programs from which data may be used and compared. The MTE description begins with a listing of the maneuver objectives presented in a succinct bullet list format. The objectives identify the specific analysis issues to be evaluated in the maneuver. A description of the maneuver execution then follows. The description is designed to provide guidelines rather than step-by-step instructions. The intent is to allow the maneuver to be performed in a consistent manner over multiple platforms and flight conditions. Next are the desired and adequate performance criteria. In the handling qualities world, such requirements are designed to facilitate use of pilot rating scales. For sUAS hazard scenario assessments, these requirements are designed to provide a means to objectively measure task performance under nominal and hazard scenario conditions, so that the impact of a given hazard can be quantified.

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The role of the pilot/operator is an important factor in evaluating and mitigating sUAS hazards. For a remote pilot that is actively engaged in flying the vehicle, issues such as latency in pilot inceptor to vehicle response may be an important factor and must be reflected in the requirements. On the other hand, an autonomous system can be considered an on-board “pilot” where the impact of the guidance, navigation, and control functions of the software must be considered in the assessments. Thus, the role of the pilot/operator will be reflected in the requirements that are linked to a given MTE. UAS operations may be:

Remotely Piloted;

Remote Pilot Assisted (delegated or supervised);

Fully Autonomous; or

A combination of the three.

The above correspond with the four levels of autonomy as defined in the DoD Unmanned Systems Integrated Roadmap23. These definitions are repeated below:

Level 1 – Human Operated: The human operator makes all decisions. The system has no autonomous control of its environment although it may have information-only responses to sensed data.

Level 2 – Human Delegated: The vehicle can perform many functions independently of human control when delegated to do so (e.g., autopilot functions). This level encompasses automatic controls, engine controls, and other low-level automation that must be activated or deactivated by human input and must act in mutual exclusion of human operation.

Level 3 – Human Supervised: The system can perform a wide variety of activities when given top-level permissions or direction by a human. Both the human and the system can initiate behaviors based on sensed data, but the system can do so only if within the scope of its currently directed tasks.

Level 4 – Fully Autonomous: The system receives goals from humans and translates them into tasks to be performed without human interaction. A human could still enter the loop in an emergency or change the goals, although in practice there may be significant time delays before human intervention occurs.

When actively engaged in flying, the pilot provides guidance, navigation, and control (GNC) functions. Autopilots can provide regulation of some of these functions, but they are not autonomous functions, they are regulators. Autonomous functions feature a decision making capability that attempts to replicate or even improve upon piloted operations. For the commercial sUAS operations to be successful in beyond visual line of sight use cases, the vehicles must operate in a predominantly autonomous mode of operation.

3. Common Mission Task Elements

For a given sUAS type (i.e., fixed wing, multi-rotor, or helicopter), there are select mission task elements that are common to any mission. These are exemplified by those listed in Table 3. A quick review of the listings exposes some of the differences between fixed wing and rotary wing missions. In general, the fixed wing aircraft will have a longer range and endurance than the rotary wing sUAS, but the fixed wing aircraft may require a more refined terminal area for launch and recovery. This may be as simple as a relatively flat terrain that has been reasonably groomed. Rotary wing aircraft, on the other hand, can launch and recover from a wide variety of terminal areas that are not available to fixed wing aircraft. On the surface, the common maneuvers for sUAS multi-rotors and helicopters are the same. However, the capabilities and limitations of the aircraft may result in unique performance requirements between the types. As these MTEs are evaluated in flight, there may also be slight modifications required for the task descriptions. Examples of common MTEs are provided in Table 4. The MTE descriptions and performance requirements were derived from fixed wing (see Ref. [22]) and rotorcraft (see Ref. [18]) handling qualities analogs. Until these MTES are evaluated in flight, the task descriptions and performance criteria must be considered preliminary.

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Table 3. Common Mission Task Elements

Fixed Wing Multi-Rotor Helicopter

Takeoff & Climb Takeoff Takeoff

Altitude Change Precision Hover Precision Hover

Flightpath Capture (Climb/Descent) Vertical Maneuver (Vertical Altitude Change)

Vertical Maneuver (Vertical Altitude Change)

Pitch/Roll Attitude Capture Lateral Reposition Lateral Reposition

Heading Capture Pullup/Pushover (Obstacle Avoidance) Pullup/Pushover (Obstacle Avoidance)

Obstacle Avoidance Descent to Landing Descent to Landing

Landing Landing Landing

Hovering Turn Hovering Turn

Table 4. Example Common Mission Task Elements


MTE: Bank Angle Capture MTE: Vertical Maneuver MTE: Lateral Reposition

Objectives:

• Evaluate ability to roll and capture a bank angle.

• Identify maneuverability limitations and oscillation tendencies.

Objectives:

• Evaluate heave damping, i.e., the ability to precisely start and stop a vertical rate.

• Evaluate vertical control power. • Identify undesirable coupling

between collective and the pitch, roll, and yaw axes.

Objectives:

• Assess roll axis and heave axis response during moderately aggressive maneuvering.

• Identify undesirable coupling between the roll controller and the other axes.

Description: • From steady, wings level flight

roll and capture a bank angle of 45 and maintain this bank angle within the specified tolerance for 5 seconds or until stable.

• Capture the 45 bank angle before achieving a maximum heading change of 10.

• Then capture and hold a bank angle of -45 and maintain this bank angle within the specified tolerance for 5 seconds or until stable.

• Finally, return to steady, wings level flight and maintain within the specified tolerance for 5 seconds or until stable.

Description:

• From a stabilized hover at an altitude of 10 ft, initiate a vertical ascent of 25 ft, stabilize for 5 seconds.

• Descend back to the initial hover position and stabilize for at least 5 seconds.

• Maintain initial heading throughout the maneuver.

Description:

• Start in a stabilized hover at 25 ft with the longitudinal axis of the rotorcraft oriented 90 degrees to a reference line marked on the ground.

• Initiate a lateral acceleration to approximately 25 kts groundspeed followed by a deceleration to laterally reposition the rotorcraft in a stabilized hover 100 ft down the course.

• The acceleration and deceleration phases shall be accomplished as single smooth maneuvers.

• The maneuver is complete when a stabilized hover is achieved.

• Maintain initial heading throughout the maneuver.

Desired Performance:

• 5 bank angle. • No more than one bank angle

overshoot for each capture. Magnitude of overshoot remains within the desired region.

• No undesirable motions that impact task performance.


• Maintain start/finish altitude within ±2 ft.

• Maintain longitudinal and lateral position within ±5 ft of a point on the ground


• The rotorcraft terminates the reposition within ±5 ft of the endpoint during the deceleration, terminating in a stable hover within this band.

• Maintain longitudinal track within ±10 ft.

• Maintain altitude within ±5 ft.

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• Actual heading should be aligned with reference heading within ±5 deg throughout maneuver.


Adequate Performance:

• 10 bank angle. • No more than one bank angle

overshoot for each capture. Magnitude of overshoot remains within the adequate region.

• No oscillations (PIO if remotely piloted or limit cycles if autonomous) that impact system stability or safety of flight.



• Maintain longitudinal and lateral position within ±10 ft of a point on the ground.



• The rotorcraft terminates the reposition within ±10 ft of the endpoint during the deceleration, terminating in a stable hover within this band.


• Maintain altitude within ±10 ft. • Actual heading should be aligned

with reference heading within ±10 deg throughout maneuver.

Note:

Tests should be conducted under Calm Wind Conditions (i.e., Winds with a Steady Component of Less than 5 kts.)

Note:


Note:


4. Specialized Mission Task Elements

For a given mission, there will be those MTEs that are unique or specialized to that mission. Examples are listed in Table 5 for fixed wing, multi-rotor, and helicopter sUAS. Similar to the common MTE set, the fixed wing specialized MTEs, in general, feature longer range and endurance. The rotary wing sUAS, on the other hand, feature specialized MTEs that take advantage of their low speed flight and hovering capabilities. Examples of specialized MTEs are provided in Table 6. As was true for the common MTEs, the task descriptions and performance criteria must be considered preliminary until these MTEs are evaluated in flight.

Table 5. Specialized Mission Task Elements

Specialized Mission Task Elements


Precision Tracking of a Fixed Ground Reference Path

(e.g., Pipeline Inspection)

Precision Tracking of a Fixed Ground Reference Path

(e.g., Roadway Inspection)

Precision Tracking of a Moving Ground Target

(e.g., Law Enforcement)

Precision Tracking of a Fixed Ground Reference Area

(e.g., Precision Agriculture)


(e.g., Precision Agriculture)


(e.g., Search and Rescue)

Cargo Drop-Off

(e.g., Package Delivery)

Cargo Drop-Off

(e.g., Emergency Response)

Pirouette

(e.g., Search and Rescue)

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Table 6. Example Specialized Mission Task Elements


MTE: Precision Tracking of a Fixed Ground Reference Area (e.g., Precision Agriculture)

MTE: Precision Hover for Cargo Drop-Off (e.g., Package Delivery)

MTE: Pirouette (e.g., Search and Rescue)

Objectives:

• Evaluate ability to precisely track a prescribed grid over a ground reference area.

• Evaluate ability to precisely control flight path.

Objectives:

• Evaluate ability to transition from translating flight to a stabilized hover over the target drop zone with precision and a reasonable amount of aggressiveness.

• Evaluate ability to maintain precise position, heading, and altitude over the target drop zone.

Objectives:

• Evaluate the ability to control position as the relative wind continuously changes with respect to heading.

• Evaluate the ability to precisely control flight path in all axes.

Description: • Initiate the maneuver in steady

level flight. • Follow a prescribed grid over a

ground reference area at the required altitude and airspeed for nominal mission operation.

• Initiate turns as geofence is approached to remain within prescribed boundaries while ensuring complete coverage of the grid area.

• Maintain required flight path throughout the maneuver.

Description:

• From a forward flight of 5 kts and at an altitude of 10 ft, attain a stabilized hover over the defined drop zone.

• Maintain the stabilized hover over the drop zone for the time duration established in the performance requirements.

Description:

• Initiate the maneuver from a stabilized hover over a point on the circumference of a 10 ft radius circle with the nose of the sUAS pointed at a reference point at the center of the circle at an altitude of approximately 10 ft.

• Accomplish a lateral translation around the circle, keeping the nose of the sUAS pointed at the reference point.

• Maintain a constant lateral groundspeed throughout the maneuver.

• Terminate the maneuver with a stabilized hover over the starting point.

• Perform the maneuver in both directions.

• The maneuver shall be accomplished in calm winds and in moderate winds from the most critical direction at the starting point.


• 5 ft of target flight path. • 10 ft of target altitude. • 5 kts of target airspeed. • Remain within all prescribed

geofences throughout the maneuver.


• Attain a stabilized hover from forward flight before exiting the desired region of the drop zone.

• Maintain a stabilized hover over the desired region of the drop zone for at least 30 seconds.

• Maintain longitudinal and lateral position over the drop zone within 1 ft, where 1 ft by 1 ft box defines the desired drop zone.

• Maintain altitude above the drop zone within 1 ft.

• No undesirable motions (bobble, overshoots/undershoots) that impact task performance during the transition to hover or stabilized hover.


• Maintain a selected reference point on the sUAS within 2 ft of the circumference of the circle.

• Maintain altitude within 2 ft. • Maintain heading so that the

reference heading of the sUAS points at the center of the circle within 5 deg.

• Achieve a stabilized hover within 5 sec after returning to the starting point.

• Maintain the stabilized hover for 5 sec.


• 10 ft of target flight path. • 20 ft of target altitude. • 10 kts of target airspeed.


• Attain a stabilized hover from forward flight before exiting the adequate region of the drop zone.


• Maintain a selected reference point on the sUAS within 5 ft of the circumference of the circle.

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• Excursions of no more than 5 ft outside of the prescribed geofences throughout the maneuver.

• Maintain a stabilized hover over the adequate region of the drop zone for at least 30 seconds.

• Maintain longitudinal and lateral position over the drop zone within 2 ft, where 2 ft by 2 ft box defines the desired drop zone.

• Maintain altitude above the drop zone within 2 ft units (feet or meters).

• No oscillations (PIO if remotely piloted or limit cycles if autonomous) that impact system stability or safety of flight during the transition to hover or stabilized hover.

• Maintain altitude within 4 ft. • Maintain heading so that the

reference heading of the sUAS points at the center of the circle within 10 deg.

• Achieve a stabilized hover within 10 sec after returning to the starting point.

• Maintain the stabilized hover for 5 sec.

Note:


Note:


Note:


5. Nominal Test Scenarios by sUAS Configuration

Appendix A contains a listing of the initial set of nominal test scenarios developed to date. It should be noted that this set is still being refined and is subject to change in the final recommended set of nominal test scenarios.

6. Future Work

To ensure meaningful baseline performance specifications, the MTE process outlined in Figure 9 must be put to the test. That is, the common and specialized set MTEs must be evaluated via flight test using representative sUAS vehicle types. As part of the evaluation process, the MTE descriptions and performance requirements are expected to be refined. Furthermore, and perhaps more importantly, sUAS test procedures will be defined that address operator mode of operation (i.e., remotely piloted, remotely monitored, or autonomous), ground station requirements, data requirements (i.e., sensors and digital data storage capabilities), safety of flight requirements (e.g., “knock it off” procedures), data analysis and reporting procedures, etc. To create a robust MTE process for hazard scenario assessment, the resulting MTEs and test procedures should be repeatable from one test organization to the next given a common sUAS test platform. Any additional common or specialized MTEs will also be identified, defined, and evaluated.

C. Preliminary Hazards-Based Test Scenarios for sUAS

A set of realistic hazards-based test scenarios are needed in order to evaluate the effectiveness of hazard mitigation strategies for reducing risk in safety-critical sUAS operations. This section provides a summary of the combined hazards set defined in Ref. [3], presents an example set of risk mitigation strategies for a selected hazard, and describes the incorporation of hazards into the MTEs developed for sUAS vehicles by configuration. A preliminary set of test scenarios for off-nominal conditions are presented for this selected hazard and a subset of the associated causal & contributing factors. Prior related work for evaluating resilience under LOC conditions was performed in the context of transport aircraft safety.24 Some of the insights gained in this prior work have been applied here.

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1. Summary of Vehicle Hazards Resulting from the sUAS Hazards Analysis of Ref. [3]

In order to develop a meaningful set of hazards-based test scenarios, a realistic set of hazards are needed. In Ref. [3], an analysis of sUAS mishaps was performed in order to identify current hazards and an analysis of sUAS use cases was performed to identify future potential hazards. From these analyses, a combined set of hazards was developed. A full set of combined hazards from Ref. [3] is provided in Appendix B, including causal and contributing factors as well as result, impacts, and hazardous outcomes relative to use case categories and operational state. Table 7 summarizes the combined hazards.

Table 7. Combined Vehicle-Level Hazards Set Based on

Analyses of Current and Future Hazards (Ref. [3])

Hazard No. Hazard VH-1 Aircraft Loss of Control (LOC) VH-2 Aircraft Fly-Away / Geofence Non-Conformance VH-3 Lost Communication / Control Link VH-4 Loss of Navigation Capability VH-5 Unsuccessful Landing VH-6 Unintentional / Unsuccessful Flight Termination

VH-7 Failure / Inability to Avoid Collision with Terrain and/or Fixed / Moving Obstacle

VH-8 Hostile Remote Takeover and Control of UAS VH-9 Rogue / Noncompliant UAS

VH-10 Rogue / Noncompliant UAS (Weaponized)

VH-11 Hostile Ground-Based Attack of UAS (e.g., Using High-Powered Rifle, UAS Counter Measure Devices, etc.)

VH-12 Unintentional / Erroneous Discharge of Weapons, Explosives, Chemicals, etc.

VH-13 Erroneous Autonomous Decisions / Actions by UAS Compromise Vehicle / Operational Safety

VH-14 Cascading Failures in Multi-UAS and Collaborative Missions

2. Vehicle-Level Hazards Mitigation Strategies

To illustrate the development of hazards-based test scenarios, an example set of mitigation strategies is defined for VH-1 from Table 7 relative to operational state. These mitigation strategies are illustrated in Table 8, and a full table is provided in Appendix C. Note that the identification of mitigation strategies is highly dependent on the causal and contributing factors of the hazard being mitigated as well as the operational state. Thus, the higher the risk of the operational environment the more extensive the set of mitigation strategies that is recommended (or required). For example, a resilient flight control system is recommended for suburban and urban / congested operations with an increasing level of capability as risk increases. As used in this paper, resilience refers to an ability to actively mitigate adverse conditions in real time. This property differs from robustness in that robustness typically refers to an ability to (passively) tolerate (without actively mitigating) uncertainties – which usually relate to modeling uncertainties (e.g., parameter uncertainties and/or unmodeled dynamics) but may or may not be related to adverse conditions (e.g., wind and turbulence conditions). The resilient control system capabilities listed in Table 8 should be capable of mitigating the causal and contributing factors listed in the table. Thus the test scenarios developed for evaluating the effectiveness of these systems must specifically account for these factors.

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Table 8. Example Mitigation Strategies for VH-1: Aircraft Loss of Control

Hazard No.

Hazard Use Case / Category

Operational State

Selected Causal / Contributing Factors

Recommended Mitigation Strategies / Safety Requirements

to Reduce Risk

VH-1

Aircraft Loss of Control (LOC)

Any / All Use Cases Associated with:

Remote / Rural Location

(Includes Precision Agriculture,

Border Patrol, Wildfire Monitoring & Control, Package Delivery, etc.)

• Single UAS Manually Controlled by Remote Pilot under VLOS

• Low-Density Airspace

• Vehicle Failures / Impairment

• Control System Failures / Malfunctions / Inadequacy

• Propulsion System Failure / Malfunction

• Weather (Includes Rain, Snow / Icing, Thunderstorms, etc.)

• Wind / Wind Shear / Turbulence (Includes Boundary Layer Effects)

• Vehicle Upset Condition / Damage

• Automated Parachute

• Automated Flight Termination System


Suburban

(Includes Package Delivery, Traffic Monitoring, Infrastructure Inspection, etc.)

• Single UAS, Semi-Autonomous Control, BVLOS

• Moderate- Density Airspace

• All Hazards Listed Above• Payload / CG Shift /

Instability

• Robustness under Varying Wind Conditions

• Resilient Flight Control System for Mitigating Wind Effects and/or Flight Control Component Failures

• Flight Termination System for Pre-Programmed Safe Landing Zones



Urban / Congested

(Includes Videography / Security at Public Events, Environmental Monitoring, etc.)

• Single / Multiple Semi- / Fully- Autonomous Control under BVLOS

• High-Density Airspace

• All Hazards Listed Above• Vehicle Damage (e.g.,

Lightning strike during long-duration missions, Damage from Explosion / Fire during Emergency Response, Radiation Exposure from HALE operations over urban areas, etc.)

• Harsh Environmental Conditions (e.g., Extreme Temperatures, etc.)

• Robustness under Varying Wind and Turbulence Conditions (Including Boundary Layer Effects)

• Resilient Flight Control System for Mitigating Wind Effects, Flight Control Component Failures, and Instabilities (e.g., CG Shifts)

• Additional Resilient Flight Control for Vehicle Impairment Conditions for Specialized Missions with High Risk of Vehicle Damage / Icing Conditions

• Flight Termination System Capable of Detecting a Safe Landing Zone in Real Time


3. Technical Approach for the Development of Hazards-Based Test Scenarios for sUAS Operations

The technical approach for developing hazards-based test scenarios for evaluating hazards mitigation strategies for sUAS operations is illustrated in Figure 10.

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Figure 10. Technical Approach for Hazards-Based Test Scenario Development for sUAS Operations

The goal is to be able to evaluate mitigation system effectiveness over the entire mission and for all key causal and

contributing factors associated with the hazard being mitigated. Coverage of all aspects of the mission is accomplished through the use of mission task elements, as described in Sections III.A and III.B, which were developed from the use case categories and specified by vehicle configuration. Coverage of the causal and contributing factors associated with the hazard is accomplished by designing them into the test scenarios. The performance / safety specifications being proposed in this paper will need to be validated via simulation evaluations, experimental flight testing, and input obtained from subject matter experts (SMEs). Thus, the flight test capability described in Section II will support the validation of the performance / safety requirements being specified in these scenarios. It is emphasized again that the scenarios presented in this paper are considered preliminary. The test scenarios should also be comprehensive enough to facilitate the identification of limitations in the mitigation system – either relative to hazard coverage or mission coverage. An example set of hazards-based test scenarios is presented in the next subsection for the resilient flight control system capabilities recommended in Table 8.

4. Example Hazards-Based Test Scenarios for VH-1: Aircraft Loss of Control

An initial set of hazards-based test scenarios is developed to assess the effectiveness of the resilient flight control mitigation system for VH-1 relative to the key causal and contributing factors provided in Table 8. Safety requirements are considered for increasing levels of population density (i.e., suburban and urban/congested). Table 9 provides a summary of the preliminary hazards-based test scenarios for each vehicle configuration, and Table 10 provides an example scenario. A set of initial test scenarios for VH-1 is provided in Appendix D. The hazards-based scenario format follows that used for the nominal MTEs developed in Sections III.B.3 and III.B.4. A preliminary format for describing minimum performance capability in degraded conditions is shown in Table 10. Two performance levels (labeled as Desired and Adequate) are proposed to enable the quantification of hazards effects (and mitigation system effectiveness) relative to the nominal performance specification for each mission task. Further research is needed to fully define these tasks and the minimum acceptable performance for various scenarios. It should be noted that the scenarios illustrated in Tables 9 and 10 and those provided in Appendix D are preliminary and subject to review and potential refinement by SMEs. Moreover, the desired and adequate performance requirements are initial estimates and still need to be validated via simulation and flight testing, as depicted in Figure 10.

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Table 9. Summary of Initial Hazards-Based Test Scenarios for VH-1: Aircraft Loss of Control

Scenario Fixed Wing (FW) Multi-Rotor (MR) Helicopter (UH)

Robustness under Wind & Turbulence Conditions

• Varying Wind Speed & Direction

• Varying Turbulence Levels





Resilience to Flight Control Component Failures

• Loss of Control Effectiveness (Elevator, Rudder, Aileron, Thrust)

• Stuck Actuator (Elevator, Rudder, Aileron)

• Loss of Control Effectiveness (Rotors)

• Stuck Rotor Speed

• Loss of Control Effectiveness (Main & Tail Rotors)


Resilience to Shifts in Center of Gravity (C.G.) Position

(e.g., Package Delivery)

• Longitudinal C.G. Shifts

• Lateral C.G. Shifts

• Vertical C.G. Shifts







Resilience to Vehicle Impairment Conditions

(e.g., due to lifting / control surface contamination, damage, etc. related to missions in harsh / extreme conditions)

• Lifting / Control Surface Contamination Effects

• Lifting / Control Surface Damage Effects (with and without associated C.G. shifts)

• Vehicle Contamination Effects

• Vehicle Damage Effects (with and without associated C.G. shifts)

• Vehicle Contamination Effects

• Vehicle Damage Effects (with and without associated C.G. shifts)

Resilience to Control Component Failures, Vehicle Instabilities, and Vehicle Impairment Conditions

(e.g., for high-risk missions in harsh / extreme conditions)

• Flight Control Component Failures

• C.G. Shifts

• Vehicle Impairment Conditions

• Wind / Turbulence Conditions


• C.G. Shifts




• C.G. Shifts



Table 10. Example Hazards-Based Test Scenario for Resilience to Flight Control Component Failures

Fixed Wing (FW) Multi-Rotor (MR) Helicopter (UH)

Resilience to Flight Control Component Failures

Objectives:

• Evaluate ability to detect / mitigate flight control component failures during all mission tasks.

• Identify resilience coverage and limitations under flight control component failures (in terms of failure type / severity and MTE effectiveness).

• Determine control limits and maneuverability constraints under control component failures.

Objectives:




Objectives:




Description:

• Initiate each nominal MTE and randomly inject an emulated control component failure (elevator, rudder, aileron, and engine

Description:

• Initiate each nominal MTE and randomly inject an emulated control component failure

Description:

• Initiate each nominal MTE and randomly inject an emulated control component failure (main and tail rotor failures), as

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thrust), as follows (and in accordance with the aircraft configuration being tested).

• Evaluate loss of control effectiveness (elevator, rudder, aileron, and engine thrust) incrementally from 0% to 100%.

• Evaluate resilience (i.e., mitigation effectiveness) to stuck control surface effects incrementally from neutral to hard-over positions (elevator, rudder, and aileron).

• Evaluate with no winds and nominal wind conditions (no turbulence)

(rotor failures), as follows (and in accordance with the aircraft configuration being tested).

• Evaluate loss of control effectiveness (rotor speed) incrementally from 0% to 100%.

• Evaluate resilience (i.e., mitigation effectiveness) to stuck rotor-speed effects incrementally from neutral to maximum levels.


follows (and in accordance with the aircraft configuration being tested).

• Evaluate loss of control effectiveness (rotor speed) incrementally from 0% to 100%.

• Evaluate resilience (i.e., mitigation effectiveness) to stuck rotor-speed effects incrementally from neutral to maximum levels.


Flight Conditions:

All FW Nominal Common MTEs Selected FW Nominal Specialized MTEs, as

Appropriate

Flight Conditions:

• All MR Nominal Common MTEs • Selected MR Nominal Specialized MTEs, as

Appropriate

Flight Conditions:

• All UH Nominal Common MTEs • Selected UH Nominal Specialized MTEs, as

Appropriate

Hazard Condition: Single Component Failure

Loss of Control Effectiveness (elevator, rudder, aileron, and engine thrust): 0%, 10%, 20%, …, 100%

Stuck Control Surface (elevator, rudder, aileron) Increments from Neutral: ±2 deg, ±4 deg, …, ± hard-over

Hazard Condition: Single Rotor Failure

Loss of Control Effectiveness (rotor speed): 0%, 10%, 20%, …, 100%

Stuck Rotor Speed Increments from Nominal: ±10%, ±20%, …, ± 100% (positive and negative values represent increments above or below the nominal value)

Hazard Condition: Single Rotor Failure

Loss of Control Effectiveness (main and tail rotor thrust): 0%, 10%, 20%, …, 100%

Stuck Rotor Speed Increments from Nominal: ±10%, ±20%, …, ± 100% (positive and negative values represent increments above or below the nominal value)

Environmental Conditions: No wind Varying levels and directions of sustained

wind conditions up to 10% above the rated wind level for vehicle operation

Environmental Conditions:

No wind Varying levels and directions of sustained


Environmental Conditions:

No wind Varying levels and directions of sustained



• ≥ 80% of Nominal Performance (Suburban)

• ≥ 90% of Nominal Performance (Urban / Congested)
















Test Variations:

• Tests at varying initial conditions within each MTE

• For Dual-Engine Vehicle Configurations, Include Single Engine Out Conditions

• Multiple Failures can be Considered to Determine Level of Available Control Redundancy

Test Variations:


• Multiple Rotor Failures Can be Considered to Evaluate Level of Available Control Redundancy

• Failures Involving Reversal of Rotor Rotational Direction Should be Considered if a Failure Mode Resulting in this Behavior is Identified

Test Variations:


• Realistic Combinations Involving Main and Tail Rotor Failures Should be Considered if a Failure Mode Resulting in this Behavior is Identified

• Failures Involving Reversal of Rotor Rotational Direction (Main or Tail Rotor) Should be Considered if a Failure Mode Resulting in this Behavior is Identified

Notes:

Evaluations should predominantly be performed using a simulation capable of characterizing off-nominal condition effects; Selected simulation results should be validated in flight testing

Notes:


Notes:


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5. Future Work

This section has described the technical approach for developing hazards-based test scenarios for use in evaluating the effectiveness and coverage of hazard mitigation systems and strategies throughout the sUAS mission. Some initial test scenarios were provided to illustrate this process for a selected vehicle-level hazard. It should be noted, however, that this initial set is still being refined and is subject to change in the final recommended set of hazards-based test scenarios being developed. Further work is needed in defining failure modes and their effects for sUAS25, 26, 27, especially multirotor configurations, and in the development of a full set of hazards-based test scenarios at the vehicle level. Test scenarios designed to assess operational safety under off-nominal and hazardous conditions and the effectiveness of contingency management systems designed to ensure operational safety are also needed.

IV. Future Directions in Experimental Flight Testing: Multi-UAS Operations As stated previously, the operation of sUAS within the UTM system is expected to migrate toward high-risk

environments associated with suburban and urban settings. It is also anticipated that future demand will necessitate a shift toward multi-UAS operations in which a single operator will be responsible for the safe operation of multiple sUAS simultaneously. This section discusses the need for establishing a multi-UAS flight test environment that facilitates integrated research and technology evaluations involving autonomy, real-time risk management and safety assurance, human-automation teaming, and V&V of increasingly autonomous systems.

A. Multi-sUAS Operations Associated with the proliferation of civil applications for sUAS is a paradigm shift to BVLOS operations with

increasing use of autonomous systems and operations under increasing levels of urban development and airspace usage. It is also anticipated that increasing demand for sUAS operations in multiple application domains will necessitate a paradigm shift towards multi-UAS operations and the use of advanced technologies that enable real-time risk assessment and safety assurance and effective dynamic human-automation teaming for real-time contingency management at the operational level. Multi-sUAS operations may involve simultaneous operation of heterogeneous vehicle types, collaborative missions, and coordinated missions involving manned air and ground vehicles. As risk increases for ensuring the safety of manned aircraft and persons on the ground (e.g., in suburban and urban environments), these operations become safety-critical and may require advanced technologies for ensuring safety under off-nominal conditions (both anticipated and unexpected). These technologies include resilient autonomous systems, real-time risk assessment and safety assurance systems, and effective human-automation teaming systems that are effective under off-nominal and hazardous conditions. Evaluation of these technologies will require new methods and tools that facilitate the exposure of system limitations and weaknesses in a research environment – so that weakness are not exposed in practice during a safety-critical operation. One such method is a flight test environment that enables integrated technology development and evaluations for multi-UAS safety-critical operations.

In order to define a multi-UAS flight test capability, the kinds of testing that would require support must be considered. Table 11 illustrates two examples of multi-UAS flight testing aimed at safety / risk evaluations, and Appendix E provides a phased build-up of these flight test capabilities from single UAS operations to the multi-UAS operations illustrated in Table 11. As illustrated in these tables, various features of the flight test capability are considered, including the Basic Idea, Use Cases supported, Hazards being considered, Mitigation / Contingency Systems being evaluated, and safety / risk indicators to be monitored (and managed). Moreover, the two examples of multi-UAS testing support increasing levels of operational complexity (in terms of density of operations) and increasing levels of operational risk (in terms of population density).

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Table 11. Examples of Multi-UAS Flight Testing for Safety / Risk Evaluations

Flight Test Features Multiple Heterogeneous Vehicles in Suburban Operations

High-Density Urban Operations

Basic Idea

• Multiple Vehicle Flight Test (BVLOS) • Use of BRS or Second Ground Station

for Safety / Risk Monitoring • Other Vehicles in Close Proximity - Actual sUAS - Simulated Manned Aircraft

• Higher-Density Multiple Vehicles (BVLOS) • Use of MOS for - Multiple Vehicle Operations - Safety / Risk Monitoring / Management • Use of BRS for Large-Scale Safety / Risk &

Contingencies Management

Use Cases • Infrastructure Inspection • Public Safety (Emulated Search /

Surveillance)

• Infrastructure Inspection • News Gathering / Traffic Monitoring • Package Delivery

Hazards

• Mid-Air Collision (MAC) • sUAS LOC and Impact of LOC

Trajectory on other sUAS / Aircraft • sUAS Fly-Away under LOC or GPS

Failure • Others

• Mid-Air Collision (MAC) • sUAS LOC and Impact of LOC Trajectory on

other sUAS / Aircraft and Urban Environment • Widespread GPS Malfunction / Failure (e.g.,

Loss or Corrupted Data) • Others

Mitigation / Contingency Actions

• Sense and Avoid (SAA) / Detect and Avoid (DAA) / Collision Avoidance System

• Flight Termination / Land System Pre-Programmed with Safe Landing Zone(s)

• Return to Base & Land (Commanded by UTM System)

• Resilient Flight Control System for LOC Prevention / Recovery

• Other

• SAA / DAA / Collision Avoidance System • Flight Termination / Land System that

Identifies Safe Landing Zone in Real Time • Rerouting of nominal UAS to accommodate

uncertain trajectory of off-nominal UAS • All Land (Commanded by UTM) • Resilient Flight Control System for LOC

Prevention / Recovery • Others

Safety Indicators

• Vehicle Health • Flight Path Compliance • Geofence / Flight Termination

Containment • Current / Predicted Trajectory under

LOC • Predicted Collision Point / Probability

• Current / Predicted Trajectories of Multiple UAS (Nominal & Off-Nominal)

• Current / Predicted Proximity to other UAS / Aircraft

• Others

Risk Indicators

• Current / Predicted LOC Trajectory • Predicted Impact Point / Area Relative to

Ground Assets and People • Predicted Collision Point / Area for

MAC

• Current / Predicted LOC Trajectory Relative to Ground & Other UAS

• Predicted Flight Termination Path Relative to Other UAS

An example concept for a test environment based on the above considerations is presented in the next section.

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B. Example Concept for Multi-UAS Experimental Testing The Airborne Subscale Transport Aircraft Research (AirSTAR) Testbed was developed for testing dynamically

scaled transport aircraft under loss of control (LOC) conditions.28, 29, 30 Figure 11 shows the current AirSTAR Testbed infrastructure. As indicated in Figure 11, the AirSTAR capability includes not only the vehicle being flown but ground infrastructure that supports experimental flight testing. This infrastructure includes a Mobile Operations Station (MOS) and a Base Research Station (BRS). The BRS enables pre-deployment testing, and the MOS is deployed to the test range to conduct the flight tests. The AirSTAR infrastructure, which currently supports single sUAS operations, could be expanded for multi-UAS operations.

Figure 11. AirSTAR Testbed Infrastructure

One potential concept for multi-UAS flight testing using the AirSTAR infrastructure is illustrated in Figures 12 – 14.

Figure 12. Utilization of the AirSTAR Mobile Operations Station (MOS) for Multi-UAS Testing

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Figure 13. Potential Utilization of MOS Engineering Stations for Multi-UAS Operations

Figure 14. Potential Utilization of AirSTAR BRS for Multi-UAS Operations

Figure 12 illustrates the interior layout of the AirSTAR MOS and provides some key test requirements. Specifically, it is proposed that the current capability of manually flying from the pilot station of the MOS be retained, and that the smaller engineering stations be utilized for managing multiple multi-UAS operations. An interconnection to a large-scale sUAS simulation is also proposed to enable high-density testing with a mix of actual and virtual vehicles being flown. Figure 13 provides an interior view of the MOS stations and illustrates a dual use for the pilot station. One potential concept is to use the pilot station as a safety management center representative of either an operator or a UTM regional safety manager. The station would provide the ability to monitor all flights simultaneously or pull up key flights of interest, and would interface with the UTM system, sUAS simulation labs, and Air Traffic Control / Air Traffic Management (ATC/ATM) emulations facilities (if needed). Another option would be to utilize the pilot station to fly a larger UAS in close proximity to the sUAS operations in order to evaluate nominal and off-nominal impacts between the two operations. Figure 14 illustrates the use of the AirSTAR BRS as part of a multi-UAS test environment. The BRS pilot station could be used to emulate higher-level real-time risk assessment and safety assurance functions (e.g., across multiple emulated / simulated regions of operation). The smaller stations in

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the BRS could be used to emulate (or host) UTM support service providers, FAA / ATC functions, and to facilitate interactions with ATM labs.

C. Future Work The preceding sections presented research considerations and a concept for multi-UAS flight testing. Much work

remains to be done in realizing such a capability and in ensuring effective support in the development and evaluation of integrated technologies that enable resilient autonomous vehicle and operational systems as well as human-automation teaming. Hardware and software considerations must also be considered (e.g., modularity).

V. Conclusion This paper summarized experimental test capabilities needed to ensure the safety of sUAS operations particularly

for safety-critical applications operating in high-risk environments. Some initial flight tests were described for evaluating the safety of several vehicle configurations under adverse conditions. These tests focused on single-UAS operations and considered control component and GPS system failures. In order to evaluate the effectiveness of hazards mitigation systems, a set of hazards-based test scenarios will be needed. An approach for developing these scenarios using Mission Task Elements was presented as well as some initial test scenarios that were defined to illustrate the approach. Further work is needed in refining the nominal MTEs (common and/or specialized) and in developing a full set of hazards-based test scenarios. This will involve obtaining input from subject matter experts, and validating the performance and safety requirements via simulation and flight testing. Finally, safety considerations were discussed for experimental testing under multi-UAS operations. An initial concept for multi-sUAS flight testing was presented, but further work is needed in realizing such a capability.

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Appendix A: Initial Set of Nominal Test Scenarios for Fixed Wing (FW), Multirotor (MR), and Unmanned Helicopter (UH) sUAS

Type Weight

FW‐N‐1 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Takeoff & Climb

• Evaluate ability to perform

takeoff ground roll in nominal

and gusty conditions.

• Evaluate handling qualities in

rotation.

• Evaluate ability to attain

reference attitude and airspeed

following takeoff.

• Evaluate ability to achieve

smooth, continuous pitch rate

to climb attitude.

• From hold position on runway centerline,

apply takeoff power and perform normal

takeoff.

• At rotation speed, rapidly attain reference

takeoff attitude.

• Adjust power to maintain climb airspeed

and continue to climb until cruise altitude is

attained.

FW‐N‐2 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Altitude Change• Evaluate ability to accurately

change altitude

• Initiate the maneuver in steady level flight.

Smoothly pitch up to a steady climb rate of at

least TBD fpm and maintain this rate until

within 10 ft of the target altitude.

• Level off at an altitude 100 ft above the

initial altitude and maintain steady

conditions for a minimum of 15 seconds.

• Then push over to return to the initial

altitude at a steady descent rate of at least

TBD fpm and maintain this rate until within

10 ft of the initial altitude.

• Level off at the initial altitude and maintain

steady conditions for a minimum of 15

seconds.

• Maintain bank angle, heading, and power

throughout the maneuver.

FW‐N‐3 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs)Flightpath Capture

(Climb/Descent)

• Evaluate ability to maintain

airspeed during initiation of

climbs and descents.

• Evaluate coupling between

airspeed and flightpath.

• From steady level flight, rapidly pitch over

and reduce power to attain a steady dive

angle of ‐5° within the specified tolerances.

• After an altitude loss of 100 ft, rapidly pitch

up and increase power to attain a steady

climb angle of 5° within the specified

tolerances.

• Smoothly level off at the initial altitude.

• Repeat the maneuver by first climbing and

then diving.

FW‐N‐4 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Pitch Attitude Capture

• Evaluate ability to pitch and

capture an attitude.

• Identify maneuverability

limitations and oscillation

tendencies.

• From steady level flight rapidly capture a

pitch attitude of at least 5° above trim and

maintain this attitude within the specified

tolerances for 5 seconds or until stable.

• Then perform subsequent captures of the

initial trim attitude, ‐5° below trim, and trim

attitude to complete the maneuver.

• Before proceeding to the next capture,

maintain each attitude within the specified

tolerances for 5 seconds or until stable.

• Maintain wings level flight within the

specified tolerances throughout the

maneuver.

Scenario Set No.

Recommended Evaluation Methods

Use Case Mission Task Element (MTE) Identifier

Vehicle ClassScenario Type

Task Objectives Mission Task Element (MTE) Description

None

None

None

None

Hazard

Desired Adequate

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±2 ft deviation of UAS

centerline from runway

centerline throughout takeoff

roll.

• ±2° deviation from reference

climb attitude (or flightpath

angle if appropriate) or �2.5 kts

deviation from climb airspeed.

• ±5° maximum bank angle.

• ±2.5° deviation from runway

heading.

• ±5 ft deviation of UAS centerline

from runway centerline throughout

takeoff roll.

• ±4° deviation from reference climb

attitude (or flightpath angle if

appropriate) or �5 kts deviation from

climb airspeed.

• ±10° maximum bank angle.

• ±5° deviation from runway

heading.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±5 ft of target altitude.

• ±2° bank angle deviation from

wings level.

• ±2° deviation in heading.


• ±5° bank angle deviation from

wings level.

• ±5° deviation in heading.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±1° deviation in flightpath

angle.

• Attain target descent and climb

angles with no more than one

overshoot. Magnitude of

overshoot remains within the

desired region.

• ±5 kt deviation in airspeed.

• ±2° deviation in flightpath angle.

• Attain target descent and climb

angles with no more than one

overshoot. Magnitude of overshoot

remains within the adequate region.

• ±10 kt deviation in airspeed.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±1° pitch attitude.

• ±2° deviation in bank angle.

• No more than one pitch

attitude overshoot for each

capture. Magnitude of overshoot

remains within the desired

region.

• No undesirable motions that

impact task performance.

• ±2° pitch attitude.

• ±5° deviation in bank angle.

• No more than one pitch attitude

overshoot for each capture.

Magnitude of overshoot remains

within the adequate region.

• No oscillations (PIO if remotely

piloted or limit cycles if

autonomous) that impact system

stability or safety of flight.

Performance RequirementsOperational Mode

Operational Environment

Tests should be conducted

under Calm Wind Conditions

(i.e., Winds with a Steady

Component of Less than 5 kts.)













Notes

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Type Weight

Scenario Set No.




Task Objectives Mission Task Element (MTE) Description Hazard

Desired Adequate

Operational Mode


Performance Requirements Notes

FW‐N‐5 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Bank Angle Capture

• Evaluate ability to roll and

capture a bank angle.

• Identify maneuverability

limitations and oscillation

tendencies.

• From steady, wings level flight roll and

capture a bank angle of 45° and maintain this

bank angle within the specified tolerance for

5 seconds or until stable.

• Capture the 45° bank angle before

achieving a maximum heading change of 10°.

• Then capture and hold a bank angle of ‐45°

and maintain this bank angle within the

specified tolerance for 5 seconds or until

stable.

• Finally, return to steady, wings level flight

and maintain within the specified tolerance

for 5 seconds or until stable.

FW‐N‐6 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Heading Capture• Evaluate ability to accurately

change heading.

• Initiate the maneuver from steady level

flight.

• Perform a 10° heading change to the right

with a bank angle of 30° and maintain this

new heading within the specified tolerances

for 10 seconds or until stable.

• Repeat the maneuver back to the original

heading, to the left 10°, and back again to the

original heading.

FW‐N‐7 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Landing

• Evaluate ability to control

horizontal and vertical

flightpath and airspeed for

landing.

• Evaluate ability to manage

sink rate and attitude in the

flare.

• Initiate the maneuver on final, on the

nominal approach conditions in landing

configuration.

• The approach angle (glideslope) shall be as

appropriate for the aircraft being tested.

• Touch down within the prescribed

touchdown parameters with the aircraft

centerline.

FW‐N‐8 Common

Analysis,

Simulation, Flight

Testing

All Fixed Wing All (≤ 55 lbs) Avoidance Maneuver

• Evaluate ability to rapidly, i.e.,

aggressively, climb/descend to

avoid an obstacle.

• Evaluate ability to return to

stabilized flight at a new

altitude.

Climb Description

From a safety of flight point of view, the best

obstacle avoidance flightpath will typically

be to climb to a higher altitude.

• From steady level flight rapidly capture and

maintain a climb rate of TBD fpm for an

altitude change of 50 ft.

• Level off and stabilize at a new altitude

above the designated obstacle avoidance

altitude.

• Minimize deviations in other axes

throughout the climb.

Descend Description

Though less desirable from a safety of flight

point of view, the best obstacle avoidance

flightpath may be to descend to a lower

altitude.

• From steady level flight rapidly capture and

maintain a descent rate of TBD fpm for an

altitude change of 50 ft.

• Level off and stabilize at a new altitude

below the designated obstacle avoidance

altitude.

• Minimize deviations in other axes

throughout the climb.

None

None

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±5° bank angle.

• No more than one bank angle



within the desired region.



• ±10° bank angle.

• No more than one bank angle



within the adequate region.





VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±2° deviation from target

heading.

• No more than one heading

overshoot. Magnitude of

overshoot remains within the

desired region.



• ±4° deviation from target heading.

• No more than one heading

overshoot. Magnitude of overshoot

remains within the adequate region.





VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Touch down within ±2.5 kts of

landing airspeed.

• Touch down within ±10 ft of

the longitudinal aim point along

the runway centerline and ±5 ft

laterally of the runway

centerline.

• No bounce and no hard landing

if touchdown sink rate is difficult

to measure).

• Touch down within ±5 kts of

landing airspeed.

• Touch down within ±20 ft of the

longitudinal aim point along the

runway centerline and ±10 ft

laterally of the runway centerline.

• No more than one bounce and no

hard landing.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ± TBD deviation in climb or sink

rate.

• ±10 ft deviation the new target

altitude.

• ± TBD deviation in climb or sink

rate.

• ±20 ft deviation the new target

altitude.

















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Type Weight

Scenario Set No.




Task Objectives Mission Task Element (MTE) Description Hazard

Desired Adequate

Operational Mode



FW‐N‐9 Specialized

Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Pipeline

Inspection)

Fixed Wing All (≤ 55 lbs)

Precision Tracking of a

Fixed Ground Reference

Path (e.g., Pipeline

Inspection)

• Evaluate ability to precisely

track a ground path.


control flightpath.


• Follow a prescribed ground path (e.g.,

pipeline, roadway, canal, etc.) for a

minimum of 2 minutes at the required

altitude and airspeed for nominal sensor

operation.

• Maintain required flightpath throughout

the maneuver.

FW‐N‐10 Specialized

Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Precision

Agriculture)




Area (e.g., Precision

Agriculture)


track a prescribed grid over a

ground reference area.


control flightpath.


• Follow a prescribed grid over a ground

reference area at the required altitude and

airspeed for nominal mission operation.

• Initiate turns as geofence is approached to

remain within prescribed boundaries while

ensuring complete coverage of the grid area.


the maneuver.

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• ±5 ft of target flightpath.


• ±5 kts of target airspeed.




VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)




• Remain within all prescribed

geofences throughout the

maneuver.




• Excursions of no more than 5 ft

outside of the prescribed geofences










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Type Weight

MR‐N‐1 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Takeoff

Evaluate ability to takeoff and

vertically ascend to waypoint

transition altitude.

Liftoff and vertically ascend to 30m.

MR‐N‐2 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Precision Hover

• Evaluate ability to transition from

translating flight to a stabilized

hover over the target hover zone

with precision and a reasonable

amount of aggressiveness.


precise position, heading, and

altitude over the target hover

zone.

• From a forward flight of 5 kts and at an

altitude of 10 ft, attain a stabilized hover

over the defined target hover zone.

• Maintain the stabilized hover over the

hover zone for the time duration

established in the performance

requirements.

MR‐N‐3 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs)

Vertical Maneuver

(Vertical Altitude

Change)

• Evaluate heave damping, i.e., the

ability to precisely start and stop a

vertical rate.

• Evaluate vertical control power.

• Identify undesirable coupling

between collective and the pitch,

roll, and yaw axes.

• From a stabilized hover at an altitude of

10 ft, initiate a vertical ascent of 25 ft,

stabilize for 5 seconds.

• Descend back to the initial hover

position and stabilize for at least 5

seconds.

• Maintain initial heading throughout the

maneuver.

MR‐N‐4 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Lateral Reposition

• Assess roll axis and heave axis

response during moderately

aggressive maneuvering.


between the roll controller and

the other axes.

• Start in a stabilized hover at 25 ft with

the longitudinal axis of the rotorcraft

oriented 90 degrees to a reference line

marked on the ground.

• Initiate a lateral acceleration to

approximately 25 kts groundspeed

followed by a deceleration to laterally

reposition the rotorcraft in a stabilized

hover 100 ft down the course.

• The acceleration and deceleration

phases shall be accomplished as single

smooth maneuvers.

• The maneuver is complete when a

stabilized hover is achieved.

• Maintain initial heading throughout the

maneuver.

Scenario Type

Scenario Set No.

Recommended Evaluation

Use Case Vehicle Class Mission Task Element (MTE) Identifier


None

None

None

None

HazardDesired Adequate

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Maintain target altitude within ±3 ft.

• Maintain longitudinal and lateral position

within ±6 ft of transition waypoint

• Heading at start of transition should be

within ±2 deg of reference heading.


• Maintain longitudinal and lateral

position within ±10 ft of transition

waypoint.



VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Attain a stabilized hover from forward

flight before exiting the desired region of

the hover zone.

• Maintain a stabilized hover over the

desired region of the hover zone for at least

30 seconds.


over the hover zone within ±1 ft, where ±1 ft

by ±1 ft box defines the desired hover zone.

• Maintain altitude above the hover zone

within ± 1 ft.

• No undesirable motions (bobble,

overshoots/undershoots) that impact task

performance during the transition to hover

or stabilized hover.


flight before exiting the adequate region

of the hover zone.


adequate region of the hover zone for at

least 30 seconds.


position over the hover zone within ±2 ft,

where ±2 ft by ±2 ft box defines the

desired hover zone.


within ± 2 ft units (feet or meters).

• No oscillations (PIO if remotely piloted

or limit cycles if autonomous) that impact

system stability or safety of flight during

the transition to hover or stabilized

hover.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



within ±5 ft of a point on the ground

• Actual heading should be aligned with

reference heading within ±5 deg throughout

maneuver.

• Maintain start/finish altitude within ±5

ft.


position within ±10 ft of a point on the

ground.


reference heading within ±10 deg

throughout maneuver.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• The rotorcraft terminates the reposition

within ±5 ft of the endpoint during the

deceleration, terminating in a stable hover

within this band.





maneuver.



deceleration, terminating in a stable

hover within this band.

• Maintain longitudinal track within ±20

ft.







Tests should be conducted under

Calm Wind Conditions (i.e.,

Winds with a Steady Component

of Less than 5 kts.)

1. Tests should be conducted




2. The hover point / zone is a

repeatable, ground‐referenced

point / zone from which the UAS

deviations are measured.









Notes

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Type WeightScenario Type

Scenario Set No.







Notes

MR‐N‐5 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs)Pullup / Pushover

(Obstacle Avoidance)

• Evaluate response at elevated

and reduced load factors and

during transition between

elevated and reduced load factors.


between pitch, roll, and yaw for

aggressive maneuvering in forward

flight.

• Evaluate ability to avoid

obstacles.

• From level unaccelerated flight that is

less than the maximum level flight

airspeed at maximum continuous power

(VH), attain a sustained positive load

factor in a symmetrical pullup.

• Transition, via a symmetrical pushover,

to a sustained negative load factor.

• Recover to level flight as rapidly as

possible.

MR‐N‐6 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Descent / Landing


control the rotorcraft position

during the final descent to a

precision landing point.

• Starting from an altitude of greater than

10 ft, maintain an essentially steady

descent to a prescribed landing point,

while maintaining reference heading.

• It is acceptable for the remote pilot or

autonomous system to arrest sink rate

momentarily to make last minute

corrections before touchdown.

MR‐N‐7 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Landing


horizontal and vertical flightpath

and airspeed for landing.

• Evaluate ability to manage sink

rate and attitude in the flare.


nominal approach conditions in landing

configuration.

• The approach angle (glideslope) shall be

as appropriate for the aircraft being

tested.


touchdown parameters with the aircraft

centerline.

MR‐N‐8 Common

Analysis,

Simulation, Flight

Testing

All Multi‐Rotor All (≤ 55 lbs) Hovering Turn

• Identify any undesirable vehicle

characteristics that may impact

task performance in a moderately

aggressive hovering turn.

• Evaluate ability to recover from a

moderate rate hovering turn with

reasonable precision.

• Identify any undesirable

interaxis coupling.

• From a stabilized hover at an altitude of

less than 20 ft, complete a 180 degree

turn.

• Perform the maneuver in both

directions.

None

None

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Attain a normal load factor of at least the

positive limit of the OFE (nL(+)) within 1

second from the initial control input.

• Maintain at least nL(+) for at least 2

seconds.

• Accomplish transition from nL(+) pullup to

a pushover of not greater than the negative

normal load factor limit of the OFE (nL(‐))

within 2 seconds.

• Maintain at least nL(‐) for at least 2

seconds.

• Maintain angular deviations in roll and yaw

within ±5 degrees from the initial

unaccelerated level flight condition to

completion of the maneuver.

• Attain a normal load factor of at least

the positive limit of the OFE (nL(+))

within 2 seconds from the initial control

input.


second.

• Accomplish transition from nL(+) pullup

to a pushover of not greater than the

negative normal load factor limit of the

OFE (nL(‐)) within 5 seconds.


second.

• Maintain angular deviations in roll and

yaw within ±10 degrees from the initial



VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Accomplish a gentle landing with a smooth

continuous descent and no undesirable

motions that may impact task performance.

• Touchdown within ±1 ft longitudinally and

±1 ft laterally of the desired touchdown

zone.

• Actual heading at touchdown should be

aligned with the reference heading within ±5

deg.

• Accomplish landing with no system

oscillations.

• Touchdown within ±2 ft longitudinally

and ±2 ft laterally of the desired

touchdown zone.


aligned with the reference heading

within ±10 deg.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Touch down within ±2.5 kts of landing

airspeed.


longitudinal aim point along the runway

centerline and ±5 ft laterally of the runway

centerline.

• No bounce and no hard landing if

touchdown sink rate is difficult to measure).

• Touch down within ±5 kts of landing

airspeed.



centerline and ±10 ft laterally of the

runway centerline.

• No more than one bounce and no hard

landing.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)


within ± 3 ft of a point on the ground.


• Stabilized final UAS heading at 180 deg.

From initial heading ± 3 deg.

• Complete turn to a stabilized hover (within

the desired window) with 10 sec. from

initiation of maneuver.


position within ± 6 ft of a point on the

ground.




• Complete turn to a stabilized hover

(within the desired window) with 15 sec.

from initiation of maneuver.

















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Scenario Set No.







Notes

MR‐N‐9 Specialized

Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Power Line

Inspection,

Pipeline

Inspection)

Multi‐Rotor All (≤ 55 lbs)



Path

• Evaluate ability to precisely track

a ground path.


control flightpath.

• Initiate the maneuver in steady level

flight.

• Follow a prescribed ground path (e.g.,

pipeline, roadway, canal, etc.) for a

minimum of 2 minutes at the required

altitude and airspeed for nominal sensor

operation.


the maneuver.


Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Search &

Rescue, Precision

Agriculture)




Area

• Evaluate ability to precisely track

a prescribed grid over a ground

reference area.


control flightpath.


flight.

• Follow a prescribed grid over a ground

reference area at the required altitude

and airspeed for nominal mission

operation.

• Initiate turns as geofence is approached

to remain within prescribed boundaries

while ensuring complete coverage of the

grid area.


the maneuver.


Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Package

Delivery)

Multi‐Rotor All (≤ 55 lbs)Precision Hover for Cargo

Drop‐Off

• Evaluate ability to transition from

translating flight to a stabilized

hover over the target drop zone

with precision and a reasonable

amount of aggressiveness.



altitude over the target drop zone.

• From a forward flight of 5 kts and at an

altitude of 10 ft, attain a stabilized hover

over the defined drop zone.

• Maintain the stabilized hover over the

drop zone for the time duration


requirements.

None

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)







VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)




• Remain within all prescribed geofences





• Excursions of no more than 5 ft outside

of the prescribed geofences throughout

the maneuver.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



the drop zone.


desired region of the drop zone for at least

30 seconds.


over the drop zone within ±1 ft, where ±1 ft

by ±1 ft box defines the desired drop zone.

• Maintain altitude above the drop zone

within ± 1 ft.







of the drop zone.


adequate region of the drop zone for at

least 30 seconds.


position over the drop zone within ±2 ft,

where ±2 ft by ±2 ft box defines the

desired drop zone.






the transition to hover or stabilized

hover.













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Type Weight

UH‐N‐1 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Takeoff

Evaluate ability to takeoff and

vertically ascend vertically to

waypoint transition altitude.

Liftoff and vertically ascend to 30m.

UH‐N‐2 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Precision Hover

• Evaluate ability to transition

from translating flight to a

stabilized hover over the target

hover zone with precision and a

reasonable amount of

aggressiveness.



altitude over the target hover

zone.

• From a forward flight of 5 kts and at

an altitude of 10 ft, attain a stabilized

hover over the defined target hover

zone.

• Maintain the stabilized hover over

the hover zone for the time duration


requirements.

UH‐N‐3 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs)

Vertical Maneuver

(Vertical Altitude Change)

• Evaluate heave damping, i.e.,

the ability to precisely start and

stop a vertical rate.

• Evaluate vertical control

power.


between collective and the

pitch, roll, and yaw axes.

• From a stabilized hover at an altitude

of 10 ft, initiate a vertical ascent of 25

ft, stabilize for 5 seconds.

• Descend back to the initial hover

position and stabilize for at least 5

seconds.

• Maintain initial heading throughout

the maneuver.

UH‐N‐4 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Lateral Reposition

• Assess roll axis and heave axis

response during moderately

aggressive maneuvering.


between the roll controller and

the other axes.

• Start in a stabilized hover at 25 ft with

the longitudinal axis of the rotorcraft

oriented 90 degrees to a reference line

marked on the ground.

• Initiate a lateral acceleration to

approximately 25 kts groundspeed

followed by a deceleration to laterally

reposition the rotorcraft in a stabilized

hover 100 ft down the course.

• The acceleration and deceleration

phases shall be accomplished as single

smooth maneuvers.

• The maneuver is complete when a

stabilized hover is achieved.

• Maintain initial heading throughout

the maneuver.

Scenario Type

Scenario Set No.


Use CaseVehicle Class Mission Task Element

(MTE) IdentifierTask Objectives

Mission Task Element (MTE) Description

None

None

None

None


VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



within ±6 ft of transition waypoint





within ±10 ft of transition waypoint.



VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



the hover zone.


desired region of the hover zone for at least

30 seconds.


over the hover zone within ±1 ft, where ±1 ft

by ±1 ft box defines the desired hover zone.


within ± 1 ft.







of the hover zone.


adequate region of the hover zone for at

least 30 seconds.


over the hover zone within ±2 ft, where ±2

ft by ±2 ft box defines the desired hover

zone.






the transition to hover or stabilized hover.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



within ±5 ft of a point on the ground



maneuver.



within ±10 ft of a point on the ground.




VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)




within this band.





maneuver.




within this band.






Operational Mode


Performance Requirements





1.) Tests should be conducted




2.) The hover point / zone is a

repeatable, ground‐referenced

point / zone from which the UAS

deviations are measured.









Notes

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Scenario Set No.





Operational Mode



UH‐N‐5 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned


Pullup/Pushover

(Obstacle Avoidance)

• Evaluate response at elevated

and reduced load factors and

during transition between

elevated and reduced load

factors.


between pitch, roll, and yaw for

aggressive maneuvering in

forward flight.

• Evaluate ability to avoid

obstacles.

• From level unaccelerated flight that

is less than the maximum level flight

airspeed at maximum continuous

power (VH), attain a sustained positive

load factor in a symmetrical pullup.

• Transition, via a symmetrical

pushover, to a sustained negative load

factor.

• Recover to level flight as rapidly as

possible.

UH‐N‐6 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Descent / Landing


control the rotorcraft position

during the final descent to a

precision landing point.

• Starting from an altitude of greater

than 10 ft, maintain an essentially

steady descent to a prescribed landing

point, while maintaining reference

heading.

• It is acceptable for the remote pilot

or autonomous system to arrest sink

rate momentarily to make last minute

corrections before touchdown.

UH‐N‐7 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Landing


horizontal and vertical

flightpath and airspeed for

landing.

• Evaluate ability to manage

sink rate and attitude in the

flare.


nominal approach conditions in

landing configuration.

• The approach angle (glideslope) shall

be as appropriate for the aircraft being

tested.


touchdown parameters with the

aircraft centerline.

UH‐N‐8 Common

Analysis,

Simulation, Flight

Testing

AllUnmanned

HelicopterAll (≤ 55 lbs) Hovering Turn


vehicle characteristics that may

impact task performance in a

moderately aggressive hovering

turn.

• Evaluate ability to recover

from a moderate rate hovering

turn with reasonable precision.


interaxis coupling.

• From a stabilized hover at an altitude

of less than 20 ft, complete a 180

degree turn.


directions.

• The maneuver shall be accomplished

in calm winds and in moderate winds

from the most critical direction. If a

critical direction has not been defined,

the turn shall begin with the wind on

the nose of the UAS.

None

None

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



second from the initial control input.


seconds.

• Accomplish transition from nL(+) pullup to

a pushover of not greater than the negative

normal load factor limit of the OFE (nL(‐))

within 2 seconds.


seconds.

• Maintain angular deviations in roll and yaw

within ±5 degrees from the initial





seconds from the initial control input.


second.

• Accomplish transition from nL(+) pullup

to a pushover of not greater than the

negative normal load factor limit of the

OFE (nL(‐)) within 5 seconds.


second.

• Maintain angular deviations in roll and

yaw within ±10 degrees from the initial



VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Accomplish a gentle landing with a smooth

continuous descent and no undesirable

motions that may impact task performance.

• Touchdown within ±1 ft longitudinally and

±1 ft laterally of the desired touchdown

zone.


aligned with the reference heading within ±5

deg.

• Accomplish landing with no system

oscillations.

• Touchdown within ±2 ft longitudinally

and ±2 ft laterally of the desired

touchdown zone.


aligned with the reference heading within

±10 deg.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Touch down within ±2.5 kts of landing

airspeed.



centerline and ±5 ft laterally of the runway

centerline.

• No bounce and no hard landing if

touchdown sink rate is difficult to measure).

• Touch down within ±5 kts of landing

airspeed.



centerline and ±10 ft laterally of the

runway centerline.

• No more than one bounce and no hard

landing.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)






• Complete turn to a stabilized hover (within

the desired window) with 10 sec. from

initiation of maneuver.






• Complete turn to a stabilized hover

(within the desired window) with 15 sec.

from initiation of maneuver.

1.) Tests should be conducted




2.) This MTE as written is not

applicable to teetering rotor

sUAS unmanned helicopters, and

could cause vehicle damage if

applied to such a configuration.













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Scenario Set No.





Operational Mode



UH‐N‐9 Specialized

Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Following a

Roadway for Law

Enforcement,

Pipeline

Inspection, etc.)

Unmanned




Path


track a ground path.


control flightpath.


flight.

• Follow a prescribed ground path

(e.g., pipeline, roadway, canal, etc.) for

a minimum of 2 minutes at the

required altitude and airspeed for

nominal sensor operation.

• Maintain required flightpath



Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Search &

Rescue, Precision

Agriculture, etc.)

Unmanned




Area


track a prescribed grid over a

ground reference area.


control flightpath.


flight.

• Follow a prescribed grid over a

ground reference area at the required

altitude and airspeed for nominal

mission operation.

• Initiate turns as geofence is

approached to remain within

prescribed boundaries while ensuring

complete coverage of the grid area.

• Maintain required flightpath



Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Emergency

Response, Package

Delivery, etc.)

Unmanned


Precision Hover for Cargo

Drop‐Off

• Evaluate ability to transition

from translating flight to a

stabilized hover over the target

drop zone with precision and a

reasonable amount of

aggressiveness.



altitude over the target drop

zone.

• From a forward flight of 5 kts and at

an altitude of 10 ft, attain a stabilized

hover over the defined drop zone.

• Maintain the stabilized hover over

the drop zone for the time duration


requirements.


Analysis,

Simulation, Flight

Testing

Specific Use Cases

(e.g., Search &

Rescue)

Unmanned

HelicopterAll (≤ 55 lbs) Pirouette

• Evaluate the ability to control

position as the relative wind

continuously changes with

respect to heading.

• Evaluate the ability to

precisely control flightpath in all

axes.

• Initiate the maneuver from a

stabilized hover over a point on the

circumference of a 10 ft radius circle

with the nose of the sUAS pointed at a

reference point at the center of the

circle at an altitude of approximately

10 ft.

• Accomplish a lateral translation

around the circle, keeping the nose of

the sUAS pointed at the reference

point.

• Maintain a constant lateral

groundspeed throughout the

maneuver.

• Terminate the maneuver with a

stabilized hover over the starting

point.


directions.

None

None

None

None

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)







VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)




• Remain within all prescribed geofences





• Excursions of no more than 5 ft outside

of the prescribed geofences throughout

the maneuver.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)



the drop zone.


desired region of the drop zone for at least

30 seconds.


over the drop zone within ±1 ft, where ±1 ft

by ±1 ft box defines the desired drop zone.


within ± 1 ft.







of the drop zone.


adequate region of the drop zone for at

least 30 seconds.


over the drop zone within ±2 ft, where ±2

ft by ±2 ft box defines the desired drop

zone.






the transition to hover or stabilized hover.

VLOS / BVLOS

All (Remote/Rural,

Suburban / Urban,

Congested)

• Maintain a selected reference point on the

sUAS within ±2 ft of the circumference of the

circle.


• Maintain heading so that the reference

heading of the sUAS points at the center of

the circle within ±5 deg.

• Achieve a stabilized hover within 5 sec

after returning to the starting point.

• Maintain the stabilized hover for ±5 sec.

• Maintain a selected reference point on

the sUAS within ±5 ft of the circumference

of the circle.


• Maintain heading so that the reference

heading of the sUAS points at the center of

the circle within ±10 deg.

• Achieve a stabilized hover within 10 sec

after returning to the starting point.

• Maintain the stabilized hover for ±5 sec.

















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Appendix B: Combined Hazards Set from Ref. [3]

Table B.3-a. Combined Hazards Set (1)

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Table B.3-b. Combined Hazards Set (2)

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Table B.3-c. Combined Hazards Set (3)

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Table B.3-d. Combined Hazards Set (4)

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Table B.3-e. Combined Hazards Set (5)

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Table B.3-f. Combined Hazards Set (6)

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Table B.3-g. Combined Hazards Set (7)

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Table B.3-h. Combined Hazards Set (8)

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Table B.3-i. Combined Hazards Set (9)

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Appendix C: Example Mitigation Strategies for VH-1

Hazard No.

Hazard Use Case / Category

Operational State

Causal / Contributing Factors Result Impacts Hazardous Outcomes

Recommended Mitigation Strategies / Safety Requirements

to Reduce Risk

VH-1

Aircraft Loss of Control (LOC)


Remote / Rural Location

(Includes Precision Agriculture,

Border Patrol, Wildfire Monitoring & Control, Package Delivery, etc.)

• Single UAS Manually Controlled by Remote Pilot under VLOS

• Low-Density Airspace

• Vehicle Failures / Impairment • Control System Failures /

Malfunctions / Inadequacy • Propulsion System Failure /

Malfunction • Weather (Includes Rain, Snow / Icing,

Thunderstorms, etc.) • Wind / Wind Shear / Turbulence

(Includes Boundary Layer Effects) • Vehicle Upset Condition / Damage • Pilot Error • Power Loss / Fuel Exhaustion • Electromagnetic Interference (EMI) • Unsuccessful Launch • Flight Control System Design /

Validation Errors / Inadequacy • Flight Control System Software

Implementation / Verification Error / Inadequacy

• Unexpected Obstacle Encounter Results in Unstable / Aggressive Avoidance Maneuver

• Bird Strike • Others

• Undesired Flight Trajectory that is Difficult to Predict

• Unpredictable / Unstable Control Response

• Uncontrolled Descent

• Vehicle Exits Assigned Geofence

• Uncontrolled Descent / Landing

• Uncontrolled Descent into Terrain / Water

• Vehicle Damage / Break-Up

• Mid-Air Collision with UAS

• Mid-Air Collision with Manned Aircraft

• Crash into Building / Obstacle Injures People

• Crash Debris Injures People on Ground

• Damage to Ground Asset Causes Fire


• Automated Flight Termination System

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Suburban

(Includes Package Delivery, Traffic Monitoring, Infrastructure Inspection, etc.)

• Single UAS, Semi-Autonomous Control, BVLOS

• Moderate- Density Airspace

• All Hazards Listed Above • Payload / CG Shift / Instability • Inadequate Resilience in Flight

Control System to Key LOC Hazards (Including Failures, Wind / Weather, etc.)

• Vehicle Instability Resulting from Attempted Retrieval of Objects of Unknown size/weight

• Vehicle Instability Resulting from Failure/Malfunction of Object Retrieval System

• Launch/Landing Instability on Water-Based Platform

• Propulsion or Vision Systems Failure / Inadequacy under Harsh Conditions (Fire, Smoke, Ash, Smog, Salty Sea Air, etc.)

• Above Results

• Potential for LOC Involving Multiple UAS under Common Causal Conditions (e.g., Unexpected Wind / Weather)

• Above Impacts Involving Multiple (Potentially Many) UAS

• Mid-Air Collision with One or More Manned Aircraft

• One or More Collisions with Critical Infrastructure

• Above Outcomes on Potentially Large Scale

• People on the Ground are Injured / Killed in Potentially Large Region or Multiple Regions

• People in One or More Manned Aircraft are Injured / Killed

• One or More Critical Infrastructure(s) are Damaged / Destroyed

• Robustness under Varying Wind Conditions

• Resilient Flight Control System for Mitigating Wind Effects and/or Flight Control Component Failures

• Flight Termination System for Pre-Programmed Safe Landing Zones



Urban / Congested

(Includes Videography / Security at Public Events, Environmental Monitoring, etc.)

• Single / Multiple Semi- / Fully- Autonomous Control under BVLOS

• High-Density Airspace

• All Hazards Listed Above • Vehicle Damage (e.g., Lightning strike

during long-duration missions, Damage from Explosion / Fire during Emergency Response, Radiation Exposure from HALE operations over urban areas, etc.)

• Harsh Environmental Conditions (e.g., Extreme Temperatures, etc.)

• Cascading Factors Involving Multi-UAS Operations

• Unexpected Battery Depletion

• Above Results

• Potential for LOC Involving Many UAS (Particularly from Design / Validation Inadequacy that Affects Multiple UAS and Multi-UAS Operations)

• Robustness under Varying Wind and Turbulence Conditions (Including Boundary Layer Effects)

• Resilient Flight Control System for Mitigating Wind Effects, Flight Control Component Failures, and Instabilities (e.g., CG Shifts)

• Additional Resilient Flight Control for Vehicle Impairment Conditions for Specialized Missions with High Risk of Vehicle Damage / Icing Conditions

• Flight Termination System Capable of Detecting a Safe Landing Zone in Real Time


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Appendix D: Initial Set of Hazards-Based Test Scenarios for FW, MR, and UH sUAS to Address VH-1: Aircraft Loss of Control

Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired Adequate

Test VariationsHazard NotesScenario Set No.



Hazard Causal & Contributing Conditions Operational Mode


Flight ConditionVehicle ClassScenario Type

Task Objectives Mission Task Element (MTE) Description Performance Requirements

FW‐H‐01Hazards‐

Based

Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)

Fixed Wing All (≤ 55 lbs)Robustness under Wind &

Turbulence Conditions

• Evaluate flight control

performance under varying

wind conditions



wind and turbulence effects

• Determine control limits and

maneuverability constraints

under varying wind and

turbulence effects

• Initiate each nominal MTE and randomly

inject varying wind speeds up to 10% above

the maximum sustained wind conditions

rated for vehicle operation and under

varying wind directions

• Repeat the above with turbulence

conditions representative of realistic

operational conditions and boundary layer

effects

• All FW Nominal

Common MTEs;

• Selected FW

Nominal

Specialized MTEs,

as Appropriate

Wind &

Turbulence None None

1.) Varying levels and

directions of sustained

wind conditions up to

10% above the rated

wind level for vehicle

operation

2.) The above sustained

wind conditions plus

varying levels of

turbulence

representative of

ambient and boundary‐

layer conditions

None None BVLOSSuburban / Urban /

Congested

≥ 90% of Nominal Performance

(Suburban)


(Urban / Congested)


(Suburban)


(Urban / Congested)

Tests at varying initial

conditions within each MTE

Evaluations should

predominantly be performed

using a simulation capable of

characterizing off‐nominal

condition effects; Selected

simulation results should be

validated in flight testing


Based

Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)


Resilience to Flight

Control Component

Failures

• Evaluate ability to detect /

mitigate flight control

component failures during all

mission tasks.

• Identify resilience coverage

and limitations under flight

control component failures (in

terms of failure type / severity

and MTE effectiveness)



under control component

failures


inject an emulated control componet failure

(elevator, rudder, aileron, and engine

thrust), as follows (and in accordance with

the aircraft configuration being tested)

• Evaluate loss of control effectiveness

(elevator, rudder, aileron, and engine thrust)

incrementally from 0% to 100%.

• Evaluate resilience (i.e., mitigation

effectiveness) to stuck control surface

effects incrementally from neutral to hard‐

over positions (elevator, rudder, aileron).

• Evaluate with no winds and nominal wind

conditions (no turbulence)

• All FW Nominal

Common MTEs;

• Selected FW

Nominal

Specialized MTEs,

as Appropriate

Flight Control

Component

Failure

Single Control Component

Failure

• Loss of Control Effectiveness

(elevator, rudder, aileron, and

engine thrust): 0%, 10%, 20%,

…, 100%

• Stuck Control Surface

(elevator, rudder, aileron)

Increments from Neutral:

±2 deg, ±4 deg, …, ± hard‐over

None

1.) No Winds




10% above the rated


operation

Note: No turbulence


Congested


(Suburban)


(Urban / Congested)


(Suburban)


(Urban / Congested)

1.) Tests at varying initial


2.) For Dual‐Engine Vehicle

Configurations, Include Single

Engine Out Conditions;

3.) Multiple Failures can be

Considered to Determine Level

of Available Control

Redundancy

Evaluations should








Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Changes in Mass

and/or C.G.

Location (e.g.,

Package / Cargo

Delivery)


Resilience to Shifts in

Vehicle Center of Gravity

(C.G.) Position

• Evaluate ability to mitigate

potential vehicle instabilities

(e.g., shifts in c.g. position)

during all mission tasks.


and limitations under vehicle

instabilities (in terms of c.g.

shift severity and MTE

effectiveness)



under vehicle instability

conditions


inject emulated vehicle instability

conditions (e.g., representative of shifts in

c.g. location under shifting and released

cargo) as follows and in accordance with the

aircraft configuration being tested

• Evaluate resilience to c.g. shifts

implemented incrementally to longitudinal,

lateral, and vertical limits



• All FW Nominal

Common MTEs;

• Selected FW

Nominal

Specialized MTEs,

as Appropriate

Vehicle Instability

Conditions

Vehicle Instability Conditions

• Aerodynamic changes

representative of shifts in c.g.

position implemented

incrementally from design

point to longitudinal limits





point to lateral limits





point to vertical limits

None

1.) No Winds




10% above the rated


operation

Note: No turbulence

None None BVLOS

Suburban / Urban,

Congested for Applicable

High‐Risk Missions (e.g.,

Package / Cargo Delivery,

Disaster / Emergency

Response, etc.)


(Suburban)


(Urban / Congested)


(Suburban)


(Urban / Congested)



2.) Simultaneous Longitudinal,

Lateral, and Vertical C.G. Shifts

(Combinations Should Include

the Worst‐Case Condition in

Each Direction)

Evaluations should








Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment


Resilience to Vehicle

Impairment Conditions

(e.g., due to lifting /

control surface

contamination, damage,

etc.)


mitigate vehicle impairment

conditions during all mission

tasks.



impairment conditions (in terms

of impairment type / severity




under vehicle impairment

conditions


inject emulated vehicle impairment

conditions (e.g., representative of lifting /

control surface contamination, damage, etc.)

as follows and in accordance with the aircraft

configuration being tested

• Evaluate resilience (i.e., detection /

mitigation effectiveness) to changes in flight

dynamics and control characteristics under

realistic vehicle impairment conditions

representative of specific high‐risk missions

(e.g., Maritime Surveillance in Alaska,

Disaster / Emergency Response under Harsh

Environmental Conditions, etc.)


representative of and combined with vehicle

damage



• All FW Nominal

Common MTEs;

• Selected FW

Nominal

Specialized MTEs,

as Appropriate

Vehicle

Impairment

Conditions

Vehicle Impairment

Conditions


representative of

contaminated lifting / control

surfaces (e.g., acretion of ice,

volcanic ash, etc.)

• Aerodynamic changes and

control surface loss

representative of vehicle

damage conditions combined

with underlying system

damage (e.g., flight control

component failures, sensor

failures, etc.) and associated

c.g. shifts

None

1.) No Winds




10% above the rated


operation

Note: No turbulence

None None BVLOS

Suburban / Urban,

Congested for Applicable

High‐Risk Missions (e.g.,

Package / Cargo Delivery,


Response, Law

Enforcement, etc.)


(Suburban)


(Urban / Congested)


(Suburban)


(Urban / Congested)



2.) For Operation in Harsh

Environments, Include

Reduced Engine Performance

(Loss of Thrust Effectiveness)

Conditions

Evaluations should







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Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired AdequateTest VariationsHazard Notes

Scenario Set No.


Use CaseMission Task Element

(MTE) IdentifierHazard Causal & Contributing Conditions Operational

Mode Operational Environment

Flight ConditionVehicle ClassScenario

TypeTask Objectives Mission Task Element (MTE) Description



Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment


Resilience to Control

Component Failures,

Vehicle Instabilities, and

Vehicle Impairment

Conditions (e.g., due to

lifting / control surface


etc.)


mitigate combinations of

adverse vehicle conditions



and limitations under

combinations of adverse vehicle

conditions (in terms of

impairment type / severity and

MTE effectiveness)



under combinations of adverse

vehicle conditions

• Evaluate under varying wind

and turbulence conditions


inject emulated adverse vehicle conditions

(as defined under FW‐H‐02 through FW‐H‐

04) in realistic combinations as described

below and in accordance with the aircraft


‐ Emulated flight control component

failures (loss of effectiveness, stuck surface)

‐ c.g. shifts implemented incrementally to

logitudinal, lateral, and vertical limits (and

worst‐case combinations)

‐ Emulated vehicle impairment conditions

(e.g., contaminated and/or damaged lifting /

control surfaces, engine impairment)

‐ Varying Wind / Turbulence Conditions

representative of ambient and boundary

layer effects

• All FW Nominal

Common MTEs

(FW‐N‐1 through

FW‐N‐8);

• Selected FW

Nominal

Specialized MTEs,

as Appropriate

Adverse Vehicle

Hazard

Combinations

from FW‐HB‐01 ‐

FW‐HB‐04

Realistic Hazard Combinations

as Specified under FW‐H‐02

through FW‐H‐04 and Selected

in Accordance with

Mission/Safety‐Critical

Requirements

None




10% above the rated


operation

2.) The above sustained

wind conditions plus

varying levels of

turbulence

representative of

ambient and boundary‐

layer conditions

None None BVLOS

Urban /Congested and

High‐Density Mission‐

Critical Operations


(Urban / Congested)


(Urban / Congested)



2.) Could also apply selected

combinations for mission‐

critical suburban operations

Evaluations should







Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired AdequatePerformance Requirements Test Variations NotesScenario

TypeScenario Set No.




Flight Condition Hazard Hazard Causal & Contributing Conditions Operational Mode


MR‐H‐01 Hazards‐Based

Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)

Multi‐Rotor All (≤ 55 lbs)Robustness under Wind

& Turbulence Conditions


performance under varying wind

conditions


performance under varying wind

and turbulence effects


maneuverability constraints under

varying wind and turbulence

effects


inject varying wind speeds up to 10%

above the maximum sustained wind

conditions rated for vehicle operation and

under varying wind directions



operational conditions and boundary layer

effects

• All MR Nominal

Common MTEs

• Selected MR

Nominal

Specialized MTEs,

as Appropriate

Wind &



directions of

sustained wind

conditions up to 10%

above the rated wind

level for vehicle

operation

2.) The above

sustained wind

conditions plus

varying levels of

turbulence

representative of

ambient and

boundary‐layer

conditions


Congested

≥ 90% of Nominal Performance (Suburban)

≥ 95% of Nominal Performance (Urban /

Congested)


(Suburban)


Congested)

Tests at varying initial conditions

(I.C.s) within each MTE

Evaluations should








Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)



Control Component

Failures


mitigate flight control component

failures during all mission tasks.

• Identify resilience coverage and

limitations under flight control

component failures (in terms of

failure type / severity and MTE

effectiveness)



control component


inject an emulated control component

failure (rotor failures), as follows (and in

accordance with the aircraft configuration

being tested)


(rotor thrust) incrementally from 0% to

100%.


effectiveness) to stuck rotor‐speed effects

incrementally from neutral to maximum

levels.

• Evaluate with no winds and nominal

wind conditions (no turbulence)

• All MR Nominal

Common MTEs

• Selected MR

Nominal

Specialized MTEs,

as Appropriate

Flight Control

Component

Failure

Single Rotor Failure

• Loss of Control

Effectiveness (rotor thrust):

0% (No Loss), 10%, 20%, …,

100% (Full Loss)


Increments from Nominal:

±10%, ±20%, …, ±100%

(Positive and negative

values represent

increments above and

below nominal value)

None

1.) No Winds


directions of

sustained wind



level for vehicle

operation

Note: No turbulence


Congested



Congested)


(Suburban)


Congested)

1.) Tests at varying initial conditions

within each MTE

2.) Multiple Rotor Failures Can be

Considered in Various Combinations

to Evaluate Level of Available Control

Redundancy

3.) Failures Involving Reversal of

Rotor Rotational Direction Should be

Considered if a Failure Mode

Resulting in this Behavior is

Identified

Evaluations should








Analysis,

Simulation, Flight

Testing

Missions Inolving

Changes in Mass

and/or C.G.

Location (e.g.,

Package / Cargo

Delivery)




(C.G.) Position


potential vehicle instabilities (e.g.,

shifts in c.g. position) during all

mission tasks.


limitations under vehicle

instabilities (in terms of c.g. shift

severity and MTE effectiveness)



vehicle instability conditions


inject emulated vehicle instability

conditions (e.g., representative of shifts in

c.g. location under shifting and released

cargo) as follows and in accordance with

the aircraft configuration being tested


implemented incrementally to

longitudinal, lateral, and vertical limits



• All MR Nominal

Common MTEs

• Selected MR

Nominal

Specialized MTEs,

as Appropriate,

But Including

MR‐N‐11

Vehicle Instability

Conditions

Vehicle Instability

Conditions


representative of shifts in

c.g. position implemented













None

1.) No Winds


directions of

sustained wind



level for vehicle

operation

Note: No turbulence

None None BVLOS

Suburban / Urban,

Congested for

Applicable High‐Risk

Missions (e.g., Package

/ Cargo Delivery,


Response, etc.)



Congested)


(Suburban)


Congested)


within each MTE

2.) Simultaneous Longitudinal,

Lateral, and Vertical C.G. Shifts

(Combinations Should Include the

Worst‐Case Condition in Each

Direction)

Evaluations should







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Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired AdequatePerformance Requirements Test Variations NotesScenario








Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment




(e.g., due to lifting

surface contamination,

damage, etc.)



conditions during all mission tasks.


limitations under vehicle

impairment conditions (in terms of


MTE effectiveness)



vehicle impairment conditions


inject emulated vehicle impairment

conditions (e.g., representative of lifting

surface contamination, damage, etc.) as

follows and in accordance with the aircraft



mitigation effectiveness) to changes in

flight dynamics and control characteristics

under realistic vehicle impairment

conditions representative of specific high‐

risk missions (e.g., Maritime Surveillance

in Alaska, Disaster / Emergency Response

under Harsh Environmental Conditions,

etc.)


representative of and combined with

vehicle damage



• All MR Nominal

Common MTEs

• Selected MR

Nominal

Specialized MTEs,

as Appropriate

Vehicle

Impairment

Conditions

Vehicle Impairment

Conditions


representative of

contaminated lifting

surfaces (e.g., acretion of

ice, volcanic ash, etc.)

• Aerodynamic changes and

control surface loss


damage conditions

combined with underlying

system damage (e.g., flight

control component failures,

sensor failures, etc.) and

associated c.g. shifts

None

1.) No Winds


directions of

sustained wind



level for vehicle

operation

Note: No turbulence

None None BVLOS

Suburban / Urban,

Congested for



/ Cargo Delivery,


Response, Law

Enforcement, etc.)



Congested)


(Suburban)


Congested)


within each MTE

2.) For Operation in Harsh

Environments, Include Reduced Rotor

Performance (Loss of Thrust

Effectiveness) Conditions

Evaluations should








Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment



Component Failures,


Vehicle Impairment


lifting surface


etc.)


mitigate combinations of adverse

vehicle conditions during all

mission tasks.


limitations under combinations of

adverse vehicle conditions (in

terms of impairment type /

severity and MTE effectiveness)

• Determine maneuverability

constraints under combinations of


• Evaluate under varying wind and

turbulence conditions


inject emulated adverse vehicle

conditions (as defined under MR‐H‐02

through MR‐H‐04) in realistic

combinations as described below and in

accordance with the aircraft configuration

being tested


failures (loss of effectiveness, stuck rotor

speed)

‐ c.g. shifts implemented incrementally

to logitudinal, lateral, and vertical limits

(and worst‐case combinations)

‐ Emulated vehicle impairment

conditions (e.g., contaminated and/or

damaged lifting surfaces, rotor thrust

impairment)

‐ Varying Wind / Turbulence Conditions

representative of ambient and boundary

layer effects

• All MR Nominal

Common MTEs

• Selected MR

Nominal

Specialized MTEs,

as Appropriate

Adverse Vehicle

Hazard

Combinations

from MR‐H‐01 ‐

MR‐H‐04

Realistic Hazard

Combinations as Specified

under MR‐H‐02 through MR‐

H‐04 and Selected in

Accordance with


Requirements

None


directions of

sustained wind



level for vehicle

operation

2.) The above

sustained wind

conditions plus

varying levels of

turbulence

representative of

ambient and

boundary‐layer

conditions

None None BVLOS



Critical Operations


Congested)


Congested)


within each MTE


combinations for mission‐critical

suburban operations

Evaluations should







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Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired AdequateTest Variations NotesScenario








UH‐H‐01Hazards‐

Based

Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)

Unmanned


Robustness under Wind &

Turbulence Conditions



wind conditions



wind and turbulence effects



under varying wind and

turbulence effects

• Initiate each nominal MTE and

randomly inject varying wind speeds

up to 10% above the maximum

sustained wind conditions rated for

vehicle operation and under varying

wind directions



operational conditions and boundary

layer effects

• All UH Nominal

Common MTEs;

• Selected UH Nominal

Specialized MTEs, as

Appropriate

Wind &


1.) Varying levels

and directions of

sustained wind

conditions up to

10% above the

rated wind level

for vehicle

operation

2.) The above

sustained wind

conditions plus

varying levels of

turbulence

representative of

ambient and

boundary‐layer

conditions


Congested



Congested)



Congested)

Tests at varying initial conditions

(I.C.s) within each MTE

Evaluations should








Based

Analysis,

Simulation, Flight

Testing

All (via Common

MTEs) & Specific

(via Specialized

MTEs)

Unmanned



Control Component

Failures


mitigate flight control

component failures during all

mission tasks.


and limitations under flight

control component failures (in

terms of failure type / severity




under control component

failures


randomly inject an emulated control

component failure (main and tail rotor

failures), as follows (and in accordance

with the aircraft configuration being

tested)


(main rotor thrust, tail rotor thrust)

incrementally from 0% to 100%.


effectiveness) to stuck rotor‐speed

effects incrementally from neutral to

maximum levels.



• All UH Nominal

Common MTEs;



Appropriate

Flight Control

Component

Failure

Single Rotor Failure

• Loss of Control

Effectiveness (main rotor

thrust, tail rotor thrust):

0% (No Loss), 10%, 20%, …,

100% (Full Loss)


Increments from Nominal:

±10%, ±20%, …, ±100%

(Positive and negative

values represent

increments above or

below nominal value)

None

1.) No Winds

2.) Varying levels

and directions of

sustained wind

conditions up to

10% above the

rated wind level

for vehicle

operation

(Including

Potentially

Destabilizing Wind

Directions)

Note: No

turbulence


Congested



Congested)



Congested)


within each MTE

2.) Realistic Combinations Involving

Main and Tail Rotor Failures Should

be Considered if a Failure Mode

Resulting in this Behavior is Identified

3.) Failures Involving Reversal of

Rotor Rotational Direction (Main or

Tail Rotor) Should be Considered if a

Failure Mode Resulting in this

Behavior is Identified

Evaluations should








Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Changes in Mass

and/or C.G.

Location (e.g.,

Package / Cargo

Delivery)

Unmanned




(C.G.) Position


potential vehicle instabilities

(e.g., shifts in c.g. position)




instabilities (in terms of c.g.

shift severity and MTE

effectiveness)



under vehicle instability

conditions


randomly inject emulated vehicle

instability conditions (e.g.,

representative of shifts in c.g. location

under shifting and released cargo,

including sling loads) as follows and in

accordance with the aircraft



implemented incrementally to

longitudinal, lateral, and vertical limits

with and without potentially

destabilizing wind conditions



• All UH Nominal

Common MTEs;



Appropriate, but

Including UH‐N‐11

Vehicle Instability

Conditions

Vehicle Instability

Conditions
















None

1.) No Winds

2.) Varying levels

and directions of

sustained wind

conditions up to

10% above the

rated wind level

for vehicle

operation

(Including

Potentially

Destabilizing Wind

Directions)

Note: No

turbulence

None None BVLOS

Suburban / Urban,

Congested for



/ Cargo Delivery,


Response, etc.)



Congested)



Congested)


within each MTE

2.) For operations involvg sling loads,

c.g. shifts should represent

reasonable variations that may be

outside of the vehicle, as well as

dynamic changes that represent a

swinging load

Evaluations should







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Type Weight Vehicle Infrastructure Environmental Operational UTM System Desired AdequateTest Variations NotesScenario









Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment

Unmanned




(e.g., due to lifting

surface contamination,

damage, etc.)



conditions during all mission

tasks.



impairment conditions (in terms

of impairment type / severity




under vehicle impairment

conditions


randomly inject emulated vehicle

impairment conditions (e.g.,

representative of lifting surface

contamination, damage, etc.) as

follows and in accordance with the

aircraft configuration being tested


mitigation effectiveness) to changes in

flight dynamics and control

characteristics under realistic vehicle

impairment conditions representative

of specific high‐risk missions (e.g.,

Maritime Surveillance in Alaska,

Disaster / Emergency Response under

Harsh Environmental Conditions, etc.)


representative of emulated vehicle

damage (as appropriate)

• Evaluate under realistic and

potentially destabilizing wind

conditions

• All UH Nominal

Common MTEs;



Appropriate

Vehicle

Impairment

Conditions

Vehicle Impairment

Conditions


representative of

contaminated rotors or

support components (e.g.,

acretion of ice, volcanic

ash, etc.)


and control component

loss of effectiveness


damage conditions (e.g.,

rotor damage) combined

with underlying system

damage (e.g., flight control

component failures,

hydraulic failure, drive

shaft failure, sensor

failures, etc.) and any

associated c.g. shifts

None

1.) No Winds

2.) Varying levels

and directions of

sustained wind

conditions up to

10% above the

rated wind level

for vehicle

operation

(Including

Potentially

Destabilizing Wind

Directions)

Note: No

turbulence

None None BVLOS

Suburban / Urban,

Congested for



/ Cargo Delivery,


Response, Law

Enforcement, etc.)



Congested)



Congested)


within each MTE






swinging load

Evaluations should








Based

Analysis,

Simulation, Flight

Testing

Missions Inolving

Harsh / Extreme

Conditions & High

Risk of Vehicle

Impairment

Unmanned



Component Failures,


Vehicle Impairment



etc.)


mitigate combinations of




and limitations under

combinations of adverse vehicle

conditions (in terms of


MTE effectiveness)



under combinations of adverse

vehicle conditions

• Evaluate under varying wind

and turbulence conditions


randomly inject emulated adverse

vehicle conditions (as defined under

MR‐H‐02 through MR‐H‐04) in realistic

combinations as described below and

in accordance with the aircraft

configuration being tested and mission

being implemented


failures (loss of effectiveness, stuck

rotor speed)

‐ c.g. shifts implemented

incrementally to logitudinal, lateral,

and vertical limits (and worst‐case

combinations)

‐ Emulated vehicle impairment

conditions (e.g., contaminated and/or

damaged rotors, rotor thrust

impairment, etc.)

‐ Varying Wind / Turbulence

Conditions representative of ambient

and boundary layer effects

• All UH Nominal

Common MTEs;



Appropriate

Adverse Vehicle

Hazard

Combinations

from MR‐H‐01 ‐

MR‐H‐04

Realistic Hazard

Combinations as Specified

under MR‐H‐02 through

MR‐H‐04 and Selected in

Accordance with


Requirements

None

1.) Varying levels

and directions of

sustained wind

conditions up to

10% above the

rated wind level

for vehicle

operation

(Including

Potentially

Destabilizing Wind

Directions)

2.) The above

sustained wind

conditions plus

varying levels of

turbulence

representative of

ambient and

boundary‐layer

conditions

None None BVLOS



Critical Operations


Congested)


Congested)


within each MTE


combinations for mission‐critical

suburban operations






swinging load

Evaluations should







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Appendix E: Multi-UAS Phased Flight Testing for Evaluation of Real-Time Risk Management Technologies

Phased Flight

Testing I. Single Vehicle II. Multiple Vehicles III. Multiple Heterogeneous Vehicles

in Suburban Operations IV. Higher Density Urban Operations

Basic Idea

• Single Vehicle Flight Test (VLOS/BVLOS)

• Use of Second Ground Station for Safety / Risk Monitoring

• Two Vehicle Flight Test -- #1: Autonomous / BVLOS -- #2: Hand-Flown / VLOS • Use of BRS or Second

Ground Station for Safety / Risk Monitoring

• Multiple Vehicle Flight Test (BVLOS)

• Use of BRS or Second Ground Station for Safety / Risk Monitoring

• Other Vehicles in Close Proximity - Actual sUAS - Simulated Manned Aircraft

• Higher-Density Multiple Vehicles (BVLOS)

• Use of MOS for - Multiple Vehicle Operations - Safety / Risk Monitoring / Management • Use of BRS for Large-Scale Safety / Risk

& Contingencies Management

Use Cases • None • Infrastructure Inspection • Fire Spotting

• Infrastructure Inspection • Public Safety (Emulated Search /

Surveillance)

• Infrastructure Inspection • News Gathering / Traffic Monitoring • Package Delivery

Hazards

• Onboard System Failure

• Vehicle Loss of Control (LOC)

• GPS System Failure • Others

• Changing No-Fly Zone(s) • Mid-Air Collision (MAC):

Non-Cooperative Vehicle #2 Entry into Vehicle #1 Airspace

• Departure from Geofence - Onboard System Failure - GPS System Failure

• Mid-Air Collision (MAC) • sUAS LOC and Impact of LOC

Trajectory on other sUAS / Aircraft • sUAS Fly-Away under LOC or GPS

Failure • Others

• Mid-Air Collision (MAC) • sUAS LOC and Impact of LOC Trajectory

on other sUAS / Aircraft and Urban Environment

• Widespread GPS Malfunction / Failure (e.g., Loss or Corrupted Data)

• Others

Mitigation / Contingency Actions

• Return to Base & Land

• Flight Termination

• SAA / DAA / Collision Avoidance System

• Flight Termination / Land System

• Risk-Based Operational Mitigation

• SAA / DAA / Collision Avoidance System

• Flight Termination / Land System Pre-Programmed with Safe Landing Zone(s)

• Return to Base & Land (Commanded by UTM System)

• Resilient Flight Control System for LOC Prevention / Recovery

• Other

• SAA / DAA / Collision Avoidance System • Flight Termination / Land System that

Identifies Safe Landing Zone in Real Time • Rerouting of nominal UAS to

accommodate uncertain trajectory of off-nominal UAS

• All Land (Commanded by UTM) • Resilient Flight Control System for LOC

Prevention / Recovery • Others

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Safety Indicators

• Vehicle Health • Flight Path

Compliance • Geofence / Flight

Termination Containment

• Vehicle Health • Flight Path Compliance • Geofence Containment • Proximity to Vehicle(s) /

Infrastructure

• Vehicle Health • Flight Path Compliance • Geofence / Flight Termination

Containment • Current / Predicted Trajectory under

LOC • Predicted Collision Point /

Probability

• Current / Predicted Trajectories of Multiple UAS (Nominal & Off-Nominal)

• Current / Predicted Proximity to other UAS / Aircraft

• Others

Risk Indicators

• Current / Predicted Trajectory

• Predicted Impact Point / Area Relative to Ground Assets and People

• Current / Predicted Trajectory • Predicted Collision Point /

Probability • Predicted Impact Point / Area

Relative to Ground Assets and People

• Current / Predicted LOC Trajectory • Predicted Impact Point / Area

Relative to Ground Assets and People

• Predicted Collision Point / Area for MAC

• Current / Predicted LOC Trajectory Relative to Ground & Other UAS

• Predicted Flight Termination Path Relative to Other UAS

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