C Advisory U.S. Department of Transportation Federal Aviation Circular Administration Subject: Human Factors Considerations in AC No: 460.15-1 Commercial Human Space Flight Date: 08/12/2024 Initiated By: ASA-1 T his Advisory Circular (AC) provides guidance on compliance with Title 14 of the Code of Federal Regulations (14 CFR) § 460.15, Human Factors. It is intended to assist prospective applicants in obtaining commercial space authorizations and operating in compliance with commercial space safety regulations. Section 460.15 requires an operator to take the precautions necessary to account for human factors that can affect a crew's ability to perform safety critical roles.
The Federal Aviation Administration (FAA) considers this AC an accepted means of compliance with the regulatory requirements of § 460.15. This guidance is not legally binding in its own right and will not be relied upon by the FAA as a separate basis for affirmative enforcement action or other administrative penalty. Conformity with the guidance is voluntary only and nonconformity will not affect rights and obligations under existing statutes and regulations.
If you have suggestions for improving this AC, you may use the Advisory Circular Feedback form at the end of this AC.
Daniel Murray Executive Director, Office of Operational Safety Commercial Space Transportation
Contents Paragraph Page
1 Purpose1
2 Applicability2
3 Related laws, Applicable Regulations and Related Documents3
4 Definition of Terms5
5 Acronyms6
6 Overview7
6.1 Scope of this AC7
6.2 Human Factors Requirements7
6.3 Human Factors Analyses7
6.4 NASA Guidance on Acceleration, Vibration, and Noise Exposure Limits8
6.5 FAA’s Recommended Practices for Human Space Flight Occupant Safety8
6.6 Verification Methodologies9
7 Design and Layout of Displays and Controls10
7.1 Instrumentation Displays and Controls10
7.2 Usability of Displays and Controls11
8 Human Factors Analysis and Testing12
8.1 Task Analysis12
8.2 Function Allocation12
8.3 Workload Analysis13
8.4 Human Error Analysis14
8.5 Inadvertent Actions15
9 Restraint and Stowage16
9.1 Stowage and Restraint of Objects16
9.2 Restraint of Crew and Space Flight Participants16
10 Vehicle Operations17
10.1 Crew Qualifications and Training17
10.2 Medical and Stress Qualifications for Crew with Safety Critical Roles17
10.3 Acceleration Exposure Protection17
10.4 Vibration Exposure Protection18
10.5 Noise Exposure Protection18
10.6 Handling Qualities19
1 PURPOSE.
1.1 This advisory circular (AC) provides guidance and an acceptable method, but not the only method, that may be used to account for human factors when crew must perform safety critical roles in accordance with Title 14 of the Code of Federal Regulations (14 CFR) § 460.15. Safety critical roles refer to crew being able to safely carry out their duties so that the vehicle will not harm the public.
1.2 Section 460.15 requires an operator to take the precautions necessary to account for human factors that can affect a crew’s ability to perform safety critical roles, including in the following safety critical areas:
• Design and layout of displays and controls;
• Mission planning, which includes analyzing tasks and allocating functions between humans and equipment;
• Restraint or stowage of all individuals and objects in a vehicle; and
• Vehicle operation, so that the vehicle will be operated in a manner that flight crew can withstand any physical stress factors, such as acceleration, vibration, and noise.
1.3 This AC presents one, but not the only, acceptable means of compliance with the associated regulatory requirements. The FAA will consider other means of compliance that an applicant may elect to present. In addition, an operator may tailor the provisions of this AC to meet its unique needs, provided the changes are accepted as a means of compliance by the FAA. Throughout this document, the word “must” characterizes statements that directly follow from regulatory text and therefore reflect regulatory mandates. The word “should” describes a requirement if electing to use this means of compliance; variation from these requirements is possible but must satisfy the regulation to constitute an alternative means of compliance. The word “may” describes variations or alternatives allowed within the accepted means of compliance set forth in this AC.
2 APPLICABILITY.
2.1 The guidance in this AC is for launch and reentry vehicle applicants and operators required to comply with 14 CFR part 460 pertaining to human factors. The guidance in this AC is for those seeking a launch or reentry vehicle operator license and a licensed operator seeking to renew or modify an existing vehicle operator license. When changes that are material to public health and safety occur within an operator’s systems or operations and involve human space flight, the human factor aspects of those changes need to be reassessed.
2.2 The material in this AC is advisory in nature and does not constitute a regulation. This guidance is not legally binding in its own right, and the FAA will not rely upon this guidance as a separate basis for affirmative enforcement action or other administrative penalty. Conformity with this guidance document (as distinct from existing statutes and regulations) is voluntary only, and nonconformity will not affect rights and obligations under existing statutes and regulations.
2.3 The material in this AC does not change or create any additional regulatory requirements, nor does it authorize changes to, or deviations from, existing regulatory requirements.
3 RELATED LAWS, APPLICABLE REGULATIONS AND RELATED DOCUMENTS.
3.1 Applicable United States Code (U.S.C.) Statute.
• Title 51 U.S.C. Subtitle V, Chapter 509, Commercial Space Launch Activities.
3.2 Related Code of Federal Regulations.
The following 14 CFR regulations must be accounted for when showing compliance with 14 CFR 460.15. The full text of these regulations can be downloaded from the U.S.
Government Printing Office e-CFR. A paper copy can be ordered from the Government Printing Office, Superintendent of Documents, Attn: New Orders, P.O. Box 371954, Pittsburgh, PA, 15250-7954.
• Section 401.5, Definitions.
• Section 401.7, Definitions.
• Section 437.55(a)(1)(iv), Hazard analysis – human errors.
• Section 450.109(b)(1)(v), Flight hazard analysis – human factors.
• Section 460.5, Crew qualifications and training.
• Section 460.7, Operator training of crew.
• Section 460.15, Human factors.
3.3 FAA Documents.
• Federal Aviation Administration (FAA). Recommended Practices for Human Space Flight Occupant Safety, Version 2.0. dated September 2023.
https://www.faa.gov/media/71481.
• U.S. Department of Transportation, FAA, Human Factors Design Standard,1 HF-STD-001B, dated December 30, 2016. https://hf.tc.faa.gov/publications/2016- 12-human-factors-design-standard/full_text.pdf.
3.4 Related U.S. Government Documents.
The documents referenced in this paragraph refer to the current revisions or regulatory authorities’ accepted revisions.
• National Aeronautics and Space Administration (NASA), Guidance for Human Error Analysis (HEA),” NASA/TM−2020-20205001486, dated April 2020.
https://ntrs.nasa.gov/api/citations/20205001486/downloads/20205001486.pdf.
1 This document covers specific design requirements such as automation of systems responses and user interfaces, designing for maintenance, visual displays and indicators, alarms, audio, and voice communications, computerhuman interfaces, keyboards and input devices, workstations and workplace design, system security, personnel safety, environment controls, anthropometry and biomechanics, and documentation.
• National Aeronautics and Space Administration (NASA), Spaceflight Human- System Standard, Volume 1, Revision C: Crew Health. NASA-STD-3001, dated September 15, 2023.
https://standards.nasa.gov/sites/default/files/standards/NASA/C//nasa-std-3001-vol- 1-rev-c-signature.pdf.
• National Aeronautics and Space Administration (NASA), Spaceflight Human- System Standard, Volume 2, Revision D: Human Factors, Habitability, And Environmental Health. NASA-STD-3001, dated September 15, 2023.
https://standards.nasa.gov/sites/default/files/standards/NASA/D/nasa-std-3001-vol- 2-rev-d-signature.pdf.
• Department Of Defense (DOD), Design Criteria Standard Human Engineering, MIL-STD-1472H, dated September 15, 2020.
https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=36903
• National Aeronautics and Space Administration (NASA), Human Systems Integration Handbook, NASA/SP-20210010952 https://ntrs.nasa.gov/api/citations/20210010952/downloads/HSI%20Handbook%20v
2.0%20092121_FINAL%20COPY.pdf
• National Aeronautics and Space Administration (NASA), Human Integration Design Handbook (HIDH). NASA/SP-2010-3407/Rev1, dated June 05, 2014.
https://www.nasa.gov/wp-content/uploads/2023/03/human-integration-designhandbook-revision-1.pdf?emrc=65f2e4c77e9ec.
Note 1: The HIDH provides guidance on implementing the requirements in NASA Space Flight Human Systems Standard, NASA-STD-3001.
• National Aeronautics and Space Administration (NASA), Human Integration Design Process (HIDP). NASA-TP-2014-218556, dated September 2014.
https://www.nasa.gov/wpcontent/uploads/2015/03/human_integration_design_processes.pdf.
Note 2: As a complimentary document to the HIDH, the HIDP describes the “how-to” processes, including methodologies and best practices NASA uses during development of crewed space systems and operations.
4 DEFINITION OF TERMS.
For this AC, the definitions from §§ 4 01.5 and 401.7 and the following apply.
4.1 Human Factors.
A multidisciplinary field that studies human capabilities, limitations, and behavior, and that applies this knowledge to the design of systems, machines, work environment, and operations. The field of human factors draws from multiple disciplines such as psychology, physiology, engineering, ergonomics, and medicine. It is applied to complex systems and operations that include aviation, maritime, military, human space flight, and nuclear energy where human performance or interaction is critical to safety.
4.2 Human Error.
An action by a human that is not intended or desired, or a failure by a human to perform an action within specified limits of accuracy, sequence, or time that fails to produce the expected result, which leads or may lead to an unwanted consequence.
4.3 Operator.
A holder of a license or permit issued by the FAA to conduct a launch or reentry.
5 ACRONYMS.
• AC – Advisory Circular
• ASA – Office of Operational Safety
• AST – Office of Commercial Space Transportation
• CFR – Code of Federal Regulations
• DOD – Department of Defense
• FAA – Federal Aviation Administration
• HEA – Human Error Analysis
• HIDH – Human Integration Design Handbook
• HIDP – Human Integration Design Processes
• HRA – Human Reliability Assessment
• NASA – National Aeronautics and Space Administration
• STD – Standard
• U.S.C. – United States Code 6
6 OVERVIEW.
6.1 Scope of this AC.
The part 460 regulatory framework is focused on public safety, which is protecting people and property that are not involved with the launch or reentry. Since 2004, Congress has maintained a “learning period” prohibiting the FAA from promulgating any regulations governing the design or operation of a launch vehicle intended to protect the health and safety of crew, government astronauts, and space flight participants, absent a serious or fatal injury, or an unplanned event during a launch or reentry.2 The current safety framework relies, in part, on an informed consent regime that requires operators to inform any individual serving as crew that the United States Government has not certified the launch or reentry vehicle as safe for carrying flight crew or space flight participants before employing or arranging for that individual to participate in a launch.3 This AC discusses the requirement of § 460.15 for operators to account for human factors that can affect a crew’s ability to safely carry out their duties to ensure that the vehicle will not harm the public (people or property not involved with the launch or reentry). This AC will be updated if and when Congress lifts the “learning period” in § 50905(c), and the FAA amends its regulations, accordingly, including any new requirements for occupant safety.
6.2 Human Factors Requirements.
In addition to § 460.15, other human factors-related requirements are in 14 CFR parts 437 and 450. For an experimental permit, the § 437.55(a)(1)(iv) hazard analysis regulation requires that hazards resulting from human error be identified and assessed with regard to public risk. For a vehicle operator license, in accordance with § 450.109(b)(1)(v), a flight hazard analysis for a launch or reentry must identify reasonably foreseeable hazards, including those resulting from human factors. Each hazard’s likelihood and severity are to be assessed and the risk elimination and mitigation measures are to be identified. Although this AC primarily addresses the part 460 human factor requirements for a launch or reentry with crew, some of the guidance in this AC is relevant or applicable to §§ 437.55(a)(1)(iv) and 450.109(b)(1)(v) such as the guidance on human error analysis and mitigating inadvertent actions.
6.3 Human Factors Analyses.
This AC covers, at a high level, the types of analyses (e.g., task, human error, workload) that an operator may conduct to account for human factors in commercial human space flight as part of mission planning per § 460.15(b). The intent is to identify these types of human factors analyses needed but not describe in detail how they should be performed.
Details on how to conduct these analyses are described in the following documents, which are listed as references in paragraph 3.4. These documents also complement and provide additional guidance to chapter 8 of this AC.
2 51 U.S.C. § 50905(c)(9).
3 14 CFR § 460.9.
• “Guidance for Human Error Analysis (HEA)” provides valuable guidance on an approach or process for performing a human error analysis.
• “Human Integration Design Processes (HIDP)” provides guidance on conducting a task analysis, workload evaluation, human error analysis as well as other types of human factors-related analyses. The HIDP content is framed around humancentered design methodologies and processes in support of human-system integration requirements.
Human-centered design is a methodology used to ensure that a design accommodates human capabilities and limitations. It is an approach to development of interactive systems that focuses on making systems usable by ensuring that the needs, capabilities, and limitations of the user (e.g., crew) are met. Human-centered design is an iterative activity that leverages data gathered from early user involvement and analyses (e.g., function allocation between users and technology, task analysis) to inform designs.
6.4 NASA Guidance on Acceleration, Vibration, and Noise Exposure Limits.
NASA Spaceflight Human-System Standard (NASA-STD-3001), Volume 24and Human Integration Design Handbook (HIDH)5 provide guidance on acceleration, vibration, and noise exposure limits. These documents also provide human factorsrelated guidance pertaining to displays and controls, restraint and stowage, and vehicle operations, which provide additional information that are applicable and complement the top-level guidance provided in chapters 7, 9, and 10 of this AC.
6.5 FAA’s Recommended Practices for Human Space Flight Occupant Safety.
Furthermore, this AC leverages or cites several human factors-related recommended practices from the FAA’s document on “Recommended Practices for Human Space Flight Occupant Safety.6” Although the recommended practices pertain to occupant (flight crew and space flight participants) safety, they may assist an operator in demonstrating compliance with § 460.15 when the safety of flight crew is essential for them to be able to perform safety critical roles.
4 NASA Spaceflight Human-System Standard, Volume 2: Human Factors, Habitability, and Environmental Health, (NASA-STD-3001, Volume 2, Revision D), dated September 15, 2023, NASA-STD-3001-Vol-2-Rev-D.pdf.
5 NASA Human Integration Design Handbook (HIDH), Volume 3407, SP-2010., Revision 2, dated October 20, 2022, Human_Integration_Design_Handbook_Revision-2.pdf.
6 FAA, Recommended Practices for Human Space Flight Occupant Safety, Version 2.0, September 2023.
https://www.faa.gov/media/71481 .
6.6 Verification Methodologies.
Verification that an operator has taken the precautions necessary to account for human factors that can affect a crew’s ability to perform safety critical roles includes testing, analysis, inspection, and demonstration. Mockups, simulators, usability testing, and human-in-the-loop testing may be used to help evaluate human-machine interfaces, human-computer interaction, and human performance such as those involving flight crew interaction with displays and controls. Usability testing to assess how well a system is designed for human use should be conducted on hardware, software, and procedures with which crew will interact to perform safety critical roles. Early identification of potential human factors-related issues during design and development is essential. This can be achieved through developmental testing to inform iterative design improvements.