Human Systems Integration (HSI) is an interdisciplinary managerial and technical approach to developing and sustaining systems which focuses on the interfaces between humans and modern technical systems. The objective of HSI is to provide equal weight to human, hardware, and software elements of system design throughout systems engineering and lifecycle logistics management activities across the lifecycle of a system. The end goal of HSI is to optimize total system performance and minimize total ownership costs. The field of HSI integrates work from multiple human centered domains of study include training, manpower (the number of people), personnel (the qualifications of people), human factors engineering, safety, occupational health, survivability and habitability.
HSI is a total systems approach that focuses on the comprehensive integration across the HSI domains, and across systems engineering and logistics support processes. The domains of HSI are interrelated: a focus on integration allows tradeoffs between domains, resulting in improved manpower utilization, reduced training costs, reduced maintenance time, improved user acceptance, decreased overall lifecycle costs, and a decreased need for redesigns and retrofits. An example of a tradeoff is the increased training costs that might result from reducing manpower or increasing the necessary skills for a specific maintenance task. HSI is most effective when it is initiated early in the acquisition process, when the need for a new or modified capability is identified. Application of HSI should continue throughout the lifecycle of the system, integrating HSI processes alongside the evolution of the system.
HSI is an important part of systems engineering projects.
History.
Military origins.
The US Navy initiated the Military Manpower versus Hardware (HARDMAN) Methodology in 1977 to address problems with manpower, personnel and training in the service. In 1980, The National Academies of Sciences, Engineering, and Medicine established the Committee on Human Factors, which was later renamed the Committee on Human Systems Integration. The modern concept of Human Systems Integration in the United States originated in 1986 as a US Army program called the Manpower and Personnel Integration (MANPRINT) program.  With ties to the academic fields of industrial engineering and experimental psychology, MANPRINT incorporated human factors engineering with manpower, personnel and training domains into an integrated discipline. MANPRINT focused on the needs and capabilities of the soldier during the development of military systems, and MANPRINT framed a human-centered focus in six domains: human factors engineering, manpower, personnel, training, health hazards and system safety. The US Marine Corps, a component of the Navy, implemented aspects of both HARDMAN and MANPRINT programs to achieve HSI objectives, issuing a formal HSI policy in Marine Corps Order 5000.22 in 1994. The US Air Force began an HSI program in 1982 as "IMPACTS". Modern HSI programs abandoned early acronyms such as HARDMAN, MANPRINT and IMPACTS over the course of the development of their HSI programs. For example, the Air Force currently manages HSI through the Air Force Office of Human Systems Integration (AFHSIO). The US Coast Guard implemented an HSI program in 2000 in the strategy and HR capability division (CG-1B) of the human resources directorate. The US Department of Homeland Security initiated an HSI program under the Science and Technology Directorate in 2007, and the Transportation Security Administration (TSA) initiated a focused HSI effort under the umbrella of DHS S&amp;T in 2018. The Federal Rail Administration (under the National Transportation Safety Board) and NASA Ames Research Center also address HSI. The United Kingdom, Canada, Australia and New Zealand have HSI programs similarly rooted in human factors and modeled after the Army MANPRINT program. In Europe HSI is known as Human Factors Integration.
Policy.
DoD acquisition policy to formalize manpower, personnel, training and safety processes started in 1988. HSI as a distinct focus area was first addressed in the Operation of the Defense Acquisition System (DODINST 5000.02) issued in 2003. Updated in 2008, this policy expanded the six domains in the MANPRINT program to seven, re-focusing systems safety as safety and occupational health, and adding habitability and survivability to the list. In 2010, the National Academy of Sciences committee on Human Systems Integration was transitioned to a board under the Division of Behavioral and Social Sciences and Education. The Board on Human Systems Integration (BOHSI) issues consensus studies, reports and proceedings on HSI research and application. A 2013 update of the DODINST 5000.02 added force protection to the survivability domain.  In 2020, the DODINST 5000.02 title and content shifted to the "Operation of the Adaptive Acquisition framework", which describes HSI activities tailored to each acquisition pathway, according to the unique characteristics of the capability being required.
The Defense Acquisition Guidebook, first published in 2002, devotes an entire chapter to manpower planning and HSI. In addition to focused discussion on each domain, the DAG emphasizes viewing HSI from a total system perspective, viewing the human components of a system as integral to the total system as any other component or subsystem. The DAG emphasizes the importance of representing HSI in all aspects of programmatic Integrated Product and Process Development, strategic planning and risk management.
The Standard Practice for Human Systems Integration (SAE 6906) was issued in 2019, and defines standard practices for procurement activities related to HSI. The standard is provided for industry to apply HSI during system design, through disposal and all related activities. This standard includes an overview of HSI and the domains, the domain relationships and tradeoffs, systems development process requirements, and a number of technical standard references
Technical Standards and requirements.
ASTM F1337-10 Standard Practice for Human Systems Integration Program Requirements for Ships and Marine Systems, Equipment and Facilities
DI-HFAC 81743 Human Systems Integration Program Plan
HSI and Systems Engineering.
The INCOSE Systems Engineering Handbook provides an authoritative reference to understand the discipline of Systems Engineering for student and practicing professionals. The human part of the system is associated with systems engineering activities from start to finish: from requirements development, to architectural design processes, verification, validation and operation. HSI is integral to the systems engineering process, and must be addressed in all program level integrated development product teams at program, technical, design, and decision reviews throughout the lifecycle of the system. The guidebook focuses on the integration of HSI into SE processes, and notes that intuitive understanding of the important role of the human as an element of a system is not enough to achieve HSI related cost and performance objectives. HSI assists engineers though the addition of human-centered domain specialists and integrators who ensure that human considerations such as usability, safety and health, maintainability and trainability are accounted for using systematic methodologies grounded in each human-centered domain
HSI trade studies and analyses are key methods of HSI that often result in insights not otherwise realized in systems engineering:. The INCOSE Systems Engineering Guidebook recommends a number of steps to effectively incorporate HSI into systems engineering processes
HSI interacts with a number of SE activities:
HSI and Logistics Support.
Planning and management for cost and performance across the lifecycle of a system are accomplished through lifecycle logistics and integrated product support. These activities ensure that the system will meet sustainment objectives and satisfy user sustainment objectives. Product Support management covers three focus areas: lifecycle management, technical management and infrastructure management. The HSI domains of training, manpower and personnel fall under infrastructure management and are among the twelve elements of logistics / product support. Design Interface, one of the twelve elements of logistics / product support, is a subcategory of technical management and includes multiple domains of HSI, including human factors, personnel, habitability, training, safety and occupational health.
Design Interface (including HSI) is the integration of quantitative systems design characteristics with functional integrated product support elements. In this element of logistics, the systems design parameters drive product support resource requirements. Product support requirements are derived to ensure the system meets availability goals, balancing design and support costs. Design interface is a leading activity that impacts all other logistics / product support elements. Reliability and maintainability are aspects of design interface that have ties to manpower, personnel and training. Maintainability is a measure of the ease and speed in which a piece of equipment or system can be restored to full functionality after a failure; it is a function of design, personnel availability and skill levels, maintenance procedures, training and test equipment. Low maintainability may increase manpower, personnel and training costs over the lifecycle of the system. Human factors engineering and usability play an important role in requirements development, definition, design development and evaluation of system support for reliability and maintainability in the operational environment. Safety and occupational health are important aspects of product support: injury, accidental equipment damage, chronic injuries and long-term health problems reduce supportability, reliability and availability
Domains.
Human Factors Engineering.
Human Factors Engineering (HFE) is an engineering discipline that ensures human capabilities and limitations in areas such as perception, cognition, sensory and physical attributes are incorporated into requirements and design. Effective HFE ensures that systems design capitalizes on, and does not exceed, the abilities of the human user population. HFE can reduce the scope of manpower and training requirements, and ensure the system can be operated maintained and supported by users, in a habitable, safe and survivable manner. HFE is concerned with designing human-systems interfaces such as: 
Technical standards and requirements:
ASTM F1166-07 Standard Practice for Human Engineering Design for Marine Systems, Equipment and Facilities
HFES-200 Human Factors Engineering of Software User Interfaces
MIL-STD 46855 Human Engineering Requirements for Military Systems, Equipment and Facilities
MIL-STD 1472 DoD Design Criteria Standard for Human Engineering
FAA Human Factors Design Standards (HFDS) HF-STD-001B
HFE Data Information Descriptions:
Human Engineering Program Plan (HEPP) DI-HFAC- 81742
Human Engineering Systems Analysis Report (HESAR) DI-HFAC-80745
Human Engineering Design Approach Document (HEDAD-M) DI-HFAC-80747
Human Engineering Design Approach Document (HEDAD-O) DI-HFAC-80746
Human Engineering Test Plan (HETP) DI-HFAC-80743
Human Engineering Test Reports (HETR) DI-HFAC-80744
Manpower.
Manpower focuses on evaluating and defining the right mix of personnel (sometimes referred to as "spaces") for people to operate, maintain and support a system. Manpower requirements should be based on task analysis and consider workload, fatigue, physical and sensory overload, environmental conditions (heat/cold) and reduced visibility. Manpower requirements are the highest cost driver for a system, and can account for up to 70% of the total lifecycle cost. Requirements are based on the full range of operations from a low operational tempo, peacetime scenario to continuous sustained operations, and should include consideration for surge operations capacity. In the manpower analysis process, labor-intensive "high driver tasks" should be examined, and targeted for engineering design changes to reduce the manpower requirement through automation, or improved usability in design. A top down functional analysis can be the basis for determinations of which functions can be eliminated, consolidated, or simplified to control manpower costs.
DoD manpower policy comes from DoD Directive 1100.4, Guidance for Manpower Management
Personnel.
The personnel domain is concerned with the human performance characteristics of the user population (cognitive, sensory and physical skills, knowledge, experience and abilities) of operators, maintainers and support staff required for a system. Cost effective engineering designs minimize personnel requirements, and keep them consistent with the user population. Systems that require new or advance personnel requirements will experience cost increases in other domains, such as training. The user group identified for a system may be referred to as the "target audience". The target audience is situated within a larger organizational structure, and recruitment, retention and personnel policies that may impact or be impacted by the new system should be considered. HSI and the personnel domain may impact policy, or policy may impact HSI. For example, the system may require additional recruitment to sustain the organizational workforce while employing the new system. An example of policy impacting HSI is increased diversity in the user population that may alter anthropometric requirements for the system and impact requirements in the HFE domain.
Manpower and personnel standards include:
Standard Practice for Manpower and Personnel SAE1010
Training.
The training domain is concerned with giving the target audience the opportunity to acquire, gain or enhance the knowledge, skills and abilities needed to operate, maintain and support a system. The target audience may be individuals or groups; training in a systems engineering / acquisition setting is focused on job-relevant knowledge, skills and abilities aimed at satisfying performance levels specific to the system being designed. Training the operators, maintainers and support personnel to conduct their respective tasks is a component of the total system and a part of delivering the intended capability of the system. This includes the integration of training concepts and strategies with elements of logistics support, including technical manuals and procedures, interactive electronic technical manuals, job performance aids,