ASTM F3705-25

1.1 This guide applies to unmanned aircraft (UA) with a maximum dimension (for example, wingspan, disk diameter) = 25 ft (= 7.68 m) operating at airspeeds below 100 kts and of any configuration or category. It is meant to be applied in a “lower risk” (low- and medium-risk airspace as described by Joint Authorities for Rulemaking on Unmanned Systems (JARUS)) airspace environment with assumed infrequent encounters with crewed aircraft; this is typically in Classes G and E airspace (below about 1200 ft (366 m) above ground level (AGL)), Classes B, C, and D (below approximately 400 ft to 500 ft (122 m to 152 m) AGL) below obstacle clearance surface (FAA Order 8260.3, as amended), or within low-altitude authorization and notification capability (LAANC) designated areas at or below the altitude specified in the facility map, or equivalent airspace internationally.

1.2 Ultimate determination of applicability will be governed by the appropriate civil aviation authority (CAA).

1.3 While some architectures may have limitations because of external conditions, this guide applies to daytime and nighttime, as well as visual meteorological conditions (VMC) and instrument meteorological conditions (IMC).

1.4 This guide is applicable to the avoidance of crewed aircraft by unmanned aircraft systems (UAS), not UA-to-UA or primary effects of terrain/obstacle/airspace avoidance (both to be addressed in future efforts). The avoidance of unmanned aircraft by crewed aircraft is also not addressed. Likewise, birds or natural hazard (for example, weather, clouds) avoidance requirements are not addressed.

1.5 In this guide, a speci?c detect-and-avoid (DAA) architecture is not de?ned and is architecture agnostic. It will, however, reference de?ned speci?c safety performance thresholds for a DAA system and present the verification process for the system to ensure safe operation.

1.6 In this guide, methods are detailed by which compliance to the requirements given in Specification F3442/F3442M should be demonstrated. Applicants may provide alternative guides for demonstrating compliance.

1.7 This guide is expected to be used by diverse contributors or actors including, but not limited to:

1.8 Except for DAA system integrators for whom all the “shalls” in this guide apply, not all aspects of this guide are universally relevant. Nonetheless, familiarity with the entire guide will inform all actors/contributors of how their contributions affect the overall DAA capability and is strongly recommended. This guide has been purposefully designed within the broader context of the ASTM Committee F38 library. When applying this guide, it is essential to consider and integrate all relevant ASTM Committee F38 standards to ensure its comprehensive and accurate implementation.

1.9 When intending to use the information provided in this guide as a means of compliance for operational or design approval, or both, it is crucial to consult with the respective oversight authorities (for example, CAA) regarding its acceptable use and application. To find out which oversight authorities have accepted this guide (in whole or in part) as an acceptable means of compliance to their regulatory requirements (hereinafter, “the Rules”), please refer to the ASTM Committee F38 webpage (www.ASTM.org/COMMITTEE/F38.htm).

1.10 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.11 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.12 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 In this guide, test methodologies and data collection metrics for demonstrating adequate design and performance characteristics of DAA systems in accordance with Specification F3442/F3442M are outlined. DAA systems are essential for BVLOS flight operations for UAS as they enable the UAS to sense (detect) potential flight hazards, notify the PIC or autopilot (alert), and command the system to react such that it is not affected by the detected hazard (avoid).

5.2 This guide is designed to align with the development of requirements for DAA system performance in Specification F3442/F3442M. As Specification F3442/F3442M is revised, this guide will be updated to reflect the most current set of “shall” statements for which the users of this guide are responsible. Maintenance of this relationship enables users of Specification F3442/F3442M to connect system performance requirements to applicable guides clearly as described in this guide.

5.3 This guide exists to guide applicants toward a standardized methodology for validating their DAA system’s component functions and overall RRs. In this guide, a minimum set of procedures and considerations are defined for demonstrating that the applicant’s DAA system meets or exceeds the requirements of Specification F3442/F3442M. A standardized process for documenting the validation efforts is provided. Standardized reporting procedures ease the communication processes between applicants and the relevant regulator or authority and provide a common basis for documenting experimental results. In Section 13, considerations and report structure are provided while material in the appendixes give brief example reports for communicating compliance with Sections 8 – 12.

5.4 Users of this guide may seek to validate a single platform for a specific-use case and operational environment or a range of platforms that fall within a bounded use case and operational environment. This guide has been developed with the intent of being agnostic to either case.

5.5 Use of Tests and Modelling—In this guide, the use of physical testing and statistical modelling throughout are referenced. For any DAA system, several flight tests may need to occur to validate the models used for fast-time simulations, as described in Section 7. Within Section 8, a framework is referenced for verifying that the models used in simulation accurately represent the flight test efforts. As the cost of flight testing is normally a major concern for DAA system designers, applicants should follow the prescribed methods developed by industry experts. Once models of the various components of the DAA system are verified, then an applicant can determine performance metrics such as loss of well clear risk ratio LR and RR through numerous simulations and flight tests.