ISO/TR 23267:2024

Technical
Report
ISO/TR 23267
First edition
Experiment results on test
2024-04
methods for detection and
avoidance (DAA) systems for
unmanned aircraft systems
Résultats d'expériences sur les méthodes de test des systèmes
de détection et d'évitement (DAA) pour les systèmes d'aéronefs
télépilotés
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test subject . 1
5 Evaluation and test method . 1
5.1 General .1
5.2 Type of detection and avoidance .1
6 Test item . 2
6.1 General .2
6.2 Modelling and simulation .2
6.2.1 General .2
6.2.2 Modelling .2
6.2.3 Simulation.2
6.3 Equipment test .2
6.4 Flight test . .3
6.4.1 General .3
6.4.2 Hardware and software used for each operational step .3
6.4.3 Range .4
Annex A (informative) Modelling and simulation . 5
Annex B (informative) Equipment test . 6
Annex C (informative) Flight test between UAS and manned aircraft, relative speed of 100 km/h .10
Annex D (informative) Flight test between UAS and manned aircraft, relative speed of
200 km/h .12
Annex E (informative) Flight test between UAS and UAS, relative speed of 100 km/h . 14
Bibliography .15

iii
Foreword
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SC 16, Unmanned aircraft systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
With rapid technological advancements, unmanned aerial systems (UAS) technology is continuing to
become more autonomous in operation and accessible to consumers. Today, the use of UAS technology is
not only prevalent for entertainment purposes but also extending into more various industrial applications
such as logistics, disaster relief, powerline inspection. There is an increasing number of UAS operations
in low altitude airspace where the safety considerations can be quite complex, especially in the context of
urban areas. All types of UAS operating in such areas must be able to avoid ground obstacles like high-rise
buildings, cranes, public utilities such as power grid and mobile network antennas, along with airspace
users that share the same airspace such as low-flying helicopters, UASs and kites. Micro-weather patterns
also pose a challenge by bringing about uncertainty, invisibility, and unpredictability.
A detection and avoidance (DAA) system is one of the key onboard systems to address these challenges.
By sensing the surrounding situations, the DAA system can examine the size and distance of a particular
obstacle, apply trajectory planning, and then calculate the possibility of collision. It orders the flight control
system to make UAS slow down, fully stop or completely offset the obstacle in a fully autonomous manner.
The function and performance of the DAA system is closely related to its safety speed, which has a direct
impact on the scope of UAS. Failure detection also causes instability and unexpected braking.
A related document about the DAA system, ISO 15964, is currently under development and will focus on
the standardization of hardware and software of each component of DAA such as sensors, computers, and
interfaces. There is an expectation that there will be further work to standardize the test and evaluation
methodologies of DAA capability to ensure that operators’ safety and quality meet the minimum
requirements, specifically for on-board/off-board DAA systems.
To achieve a safe and secure operating environment, it is significant to develop a technical report that provides
examples for test results for the safety and quality of DAA systems. This document will offer reference to
latest, detailed real-world applications of modelling and simulation, equipment tests, and flight tests.

v
Technical Report ISO/TR 23267:2024(en)
Experiment results on test methods for detection and
avoidance (DAA) systems for unmanned aircraft systems
1 Scope
This document provides a report on tests that were performed to ensure the "safety and quality"
requirements of detection and avoidance (DAA) systems used between UASs and other objects, including
aircraft. This document describes test methods and the results of related experiments, which successfully
meet the requirements of a DAA system architecture with radar and optical sensors.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Test subject
DAA targets break down into cooperative, non-cooperative, and other hazards as defined in ISO 21384-3:2023,
Table 1 and Table 2. The test subject covered in this document is the applications of non-cooperative DAA
systems that are installed onboard the UAS for the operational procedure defined in ISO 21384-3.
5 Evaluation and test method
5.1 General
This document is expected to serve as a useful reference for the standardization work on the test and
evaluation methods of DAA capability to ensure that operators’ safety and quality meet the minimum
requirements.
5.2 Type of detection and avoidance
This document’s applications of DAA systems are limited to test evaluations of avoidance of aircraft
approaching in flight, including helicopters flying at high speed to the proximity of UAS in flight.
Flight tests to evaluate the avoidance action are consistent with the 6-step operational procedure defined
in ISO 21384-3. The applicable relative speed varies across different applications of DAA systems, while this
document is limited to the test method of manned aircraft and UAS flying at the relative speed of up to
200 km/h and of UAS and UAS flying at the relative speed of up to 100 km/h.

6 Test item
6.1 General
There are three applications for the test item: modelling and simulation, equipment test and flight test.
6.2 Modelling and simulation
6.2.1 General
The purpose of modelling is to set the parameters used in the simulation process to enable the simulation-
based evaluation of collision avoidance performance. For the detail of the experiment result, see Annex A.
6.2.2 Modelling
6.2.2.1 General
Examples of modelling subjects are avoidance mobility performance and visibility. 6.2.2.2 and 6.2.2.3 show
possible evaluations of each modelling subject.
6.2.2.2 Mobility performance
The mobility performance of UAS when performing detection and avoidance is evaluated. In the evaluation,
the UAS makes several manoeuvres such as lateral movements, yawing, ascending, descending, acceleration
and slowing down, while the ground equipment that consists of a high-speed camera, position measuring
device, and anemometer measures and records the avoidance mobility performance.
6.2.2.3 Visibility
The visibility of UAS from the perspective of manned aircraft as well as the visibility of manned aircraft
via optical sensors onboard the UAS are evaluated. In the evaluation, a safety margin distance is secured
between the UAS and the manned aircraft, and the UAS moves away from the manned aircraft until the
visibility reaches its limit, while the ground equipment that consists of a visibility meter measures the
visibility.
6.2.3 Simulation
In the simulation stage, the avoidance performance is evaluated with several parameters using sensor
[3]
models. Examples of parameters that compose different simulation patterns are shown in Table 1. The
evaluation is undertaken based on the following four items: radar detection, image recognition, avoidance,
and recovery.
Table 1 — Examples of parameters setting in simulation
Parameters Values
Angle of Intersection 360 degrees at 15 degrees interval (24 patterns)
Route offset from -600 m to 600 m at 100 m interval (13 patterns)
Altitude gap -60 m, 0 m, 60 m (3 patterns)
Detection targets 2 aircrafts (2 patterns)
6.3 Equipment test
The equipment test is undertaken for the purpose of evaluating the equipment performance of detection of
manned aircraft and UAS. In the evaluation, the performance is evaluated based on whether the equipment
performs appropriately to obtain information required for avoidance. In each test, the UAS performs

simulated avoidance manoeuvres to enable the evaluation of the detection performance of the manned
aircraft or the UAS in flight. For the detail of the experiment result, see Annex B.
6.4 Flight test
6.4.1 General
The flight test for ensuring the performance of detection of manned aircraft and UAS is undertaken in a
consistent manner with the 6-step operational procedure defined in ISO 21384-3. A DAA path is generated
to perform the detection and avoidance. The path can be consistent with the steps that are defined in
accordance with ISO 21384-3, although the flight test shown in Annex C was carried out in 5 steps where the
th th
6 step was merged with the 5 step of returning to the original route.
6.4.2 Hardware and software used for each operational step
Table 2 shows the hardware and software used for each operational step. Depending on the relative speed
requirements of targets approaching the own ship, Annex C/D or E can be used as a reference for the
hardware and software subsystems to realize the operational steps outlined in ISO 21384-3. The speed
values are derived from conditions set for the flight tests.
Table 2 — Hardware & software used for each operational step
Annex C/D
Annex E
DAA operational proce-
DAA test result
dure DAA system
DAA test result
(Relative speed of
(ISO 21384-3:2023, (e.g. ISO 15964)
(Relative speed of
100 km/h and 200 km/h
Clause 11)
100 km/h for UAS)
for manned aircraft)
Operational steps Hardware and software Hardware and software Hardware and software
Detection of object Radar Radar Optical sensor
(camera)
Recognize target Optical sensor Optical sensor Optical sensor
(camera) (camera) (camera)
Manoeuvres Processing unit Processing unit Processing unit
(autonomous management (autonomous management
system) system)
Check manoeuvres result Optical sensor Optical sensor Optical sensor
a a
(camera) (camera) (camera)
Return to original route Optical sensor Optical sensor Optical sensor
(camera) (camera) (camera)
b b
6 Fly on original route Processing unit Processing unit Processing unit
a
In ISO 21384-3, the detection and avoidance are realized using optical sensors (cameras). However, step 4 is omitted in
experimental results mentioned in the Annexes. Nonetheless, the functionality of each sensor in the steps leading up to the
avoidance manoeuvre is the same as specified in ISO 21384-3, providing evidence that it can demonstrate the avoidance of a
manned aircraft flying at a relative speed of 200 km/h and a UAS flying at a relative speed of 100 km/h.
b
The detection and avoidance test results in the Annex are presented in 5 steps, which is 1 step fewer than the 6 steps
...