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

Available format(s)

Hardcopy , PDF

Language(s)

English

Published date

11-19-2021

Publisher

American Society for Testing and Materials

1.1The scope of this practice includes the following:

1.1.1A set of components that comprise an RTA system.

1.1.2Requirements and best practices to determine safe boundaries and RTA system coverage.

1.1.3Requirements and best practices for an RTA system and RTA components, as applicable.

1.1.4Appendixes with examples that demonstrate key RTA system concepts.

1.2RTA 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.).

1.3This 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.

1.4The 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.

1.5The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.6Table 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
		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

1.7This 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.

1.8This 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.

Committee	F 38
DocumentType	Standard Practice
Pages	21
PublisherName	American Society for Testing and Materials
Status	Current
Supersedes	ASTM F 3269 : 2017

ASTM F 3196 : 2018	Standard Practice for Seeking Approval for Beyond Visual Line of Sight (BVLOS) Small Unmanned Aircraft System (sUAS) Operations
ASTM F 3341/F3341M : 2020 : REV A	Standard Terminology for Unmanned Aircraft Systems

ASTM F 3341/F3341M : 2020 : REV A	Standard Terminology for Unmanned Aircraft Systems
ASTM F 3341/F3341M : 2022	Standard Terminology for Unmanned Aircraft Systems
ASTM F 3341/F3341M : 2023	Standard Terminology for Unmanned Aircraft Systems