ASTM F3269-21
Standard Practice for Methods to Safely Bound Behavior of Aircraft Systems Containing Complex Functions Using Run-Time Assurance

Standard No.

ASTM F3269-21

Release Date

2021

Published By

American Society for Testing and Materials (ASTM)

Latest

ASTM F3269-21

Scope

1.1 The scope of this practice includes the following: 1.1.1 A set of components that comprise an RTA system. 1.1.2 Requirements and best practices to determine safe boundaries and RTA system coverage. 1.1.3 Requirements and best practices for an RTA system and RTA components, as applicable. 1.1.4 Appendixes with examples that demonstrate key RTA system concepts. 1.2 RTA components are required to meet the design assurance level dictated by a safety assessment process. Guidance for the safety assessment process may be found in references appropriate for the intended operations (ARP4754A, ARP4761, Practice F3178, etc.). 1.3 This practice was developed with UAS in mind. It may be applicable for aspects of manned aircraft certification/ approval, as well as aviation ground systems. The scope of this practice is also envisioned to allow a variety of aircraft implementations where a human may perform the role of either the Complex Function or a Recovery Function. 1.4 The scope of this practice does not cover aspects of hardware/software integration. These should be considered separately during the development process. NOTE 1—This practice does not suggest a one-size-fits-all strategy knowing that not all use cases may fit well into this architecture. There may exist additional components required to satisfy specific applications to the practice. 1.5 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 Table of Contents: Title Section Introduction Background Scope 1 Referenced Documents 2 ASTM Standards 2.1 FAA Advisory Circular 2.2 RTCA Standards 2.3 SAE Standards 2.4 Terminology 3 Unique and Common Terminology 3.3 Definitions of Terms Specific to This Standard 3.4 Abbreviations 3.5 Significance and Use 4 RTA Functional Architecture 5 Overall Architecture 5.4 Components and Interfaces 5.4.1 Title Section RTA System Coverage 5.4.2 RTA Scenarios 5.4.3 Event Sequencing and Timing 5.4.3.8 Best Practices 5.4.4 Requirements 5.4.5 RTA Interfaces 5.5 Input Manager 5.6 Description 5.6.1 Requirements 5.6.2 Safety Monitor 5.7 Requirements 5.7.2 RTA Switch 5.8 Description 5.8.1 Requirements 5.8.2 Recovery Function 5.9 Description 5.9.1 Best Practices 5.9.2 Requirements 5.9.3 Keywords 6 Ground Collision Avoidance System (GCAS) as an Example RTA Appendix X1 Introduction Unassured Function X1.1 RTA Required Inputs X1.2 RTA Input Manager X1.3 Safety Monitor X1.4 Recovery Function X1.5 RTA Switch X1.6 Vehicle Management System X1.7 Machine Learning AI Autopilot (MLAA) Appendix X2 Introduction Assured and Unassured Data X2.1 Input Manager X2.2 Complex Function X2.3 Safety Monitors X2.4 Recovery Control Function X2.5 RTA Switch X2.6 Summary X2.7 Run-Time Assurance for a Neural Network-Based Adaptive Flight Control of an Unmanned Aircraft Appendix X3 Visual Line-of-Sight Operations X3.1 Beyond Visual Line-of-Sight Operation X3.2 Run-Time Assurance for Risk-Based Operation Appendix X4 Example Implementation of Timing and Latency Requirement Appendix X5 References 1.7 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. 1.8 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. 1 This practice is under the jurisdiction of ASTM Committee F38 on Unmanned Aircraft Systems and is the direct responsibility of Subcommittee F38.01 on Airworthiness. Current edition approved July 15, 2021. Published November 2021. Originally approved in 2017. Last previous edition approved in 2017 as F3269–17. DOI: 10.1520/F3269-21. F3269 − 21 2 8QLYHUVLW\RI7RURQWR 8QLYHUVLW\RI7RURQWR SXUVXDQWWR/LFHQVH$JUHHPHQW1RIXUWKHUUHSURGXFWLRQVDXWKRUL]HG 'RZQORDGHGSULQWHGE\ &RS\ULJKWE\$670,QW O DOOULJKWVUHVHUYHG :HG'HF*07 2. Referenced Documents

ASTM F3269-21 Referenced Document

• ASTM F3060 Standard Terminology for Aircraft
• ASTM F3178 Standard Practice for Operational Risk Assessment of Small Unmanned Aircraft Systems (sUAS)
• ASTM F3341/F3341M Standard Terminology for Unmanned Aircraft Systems*， 2023-01-15 Update
• SAE ARP4761 Guidance on the safety assessment process for civil aircraft, systems and equipment

ASTM F3269-21 history

• 2021 ASTM F3269-21 Standard Practice for Methods to Safely Bound Behavior of Aircraft Systems Containing Complex Functions Using Run-Time Assurance
• 2017 ASTM F3269-17 Standard Practice for Methods to Safely Bound Flight Behavior of Unmanned Aircraft Systems Containing Complex Functions