A program’s/project’s HSI approach should be tailored to include the use of various products and tools as appropriate. Note, however, that HSI data is often integrated with other data in a
standard product of the program/project and not uniquely an HSI product. Any product could have HSI implications; human considerations naturally occur as part of effective capability- based systems engineering.
7.9.5.1 HSI Plan
An HSI Plan is the focal HSI product for a program/project since it serves as the roadmap for HSI implementation. An outline for a program/project HSI plan is in appendix R of this
document. As long as the intent and content of an HSI Plan are captured, the HSI Plan may be a stand-alone systems engineering product, or it may be incorporated into a particular
program’s/project’s SEMP or program/project plan. (A stand-alone SEMP and HSI Plan are recommended for programs and large projects; having the HSI Plan incorporated into the SEMP or program / project plan may be appropriate for small projects.) If the plan is stand-alone, the parties responsible for systems engineering and HSI should ensure that the HSI Plan is aligned with the SEMP. The HSI Plan defines how human system considerations are integrated into the full systems engineering design, verification, and validation life cycle. The HSI Plan is a living document with updates to be made at significant program/project milestones. NPR 7123.1 states that the HSI Plan is first developed to support SRR, with updates required at SDR, MDR/PDR, and CDR that document the implementation of an HSI design approach to the system and its mission and that demonstrate how the design accommodates human capabilities and limitations. The HSI Plan should indicate how HSI will document issues, risks, and their mitigation as they are worked during the life cycle. By developing and executing the HSI Plan, the PM expends the effort—in conjunction with designated parties responsible for the program’s/project’s systems engineering and HSI implementation—to integrate, capture, and track HSI metrics throughout the life cycle of the program to increase safety, total system performance, and mission success.
An HSI checklist or electronic scorecard may be used to support implementation of a program- / project-specific HSI Plan. The checklist can serve as a field guide of HSI considerations at each phase of the systems engineering life cycle and to help measure design compliance with HSI requirements. At each SE milestone, an evaluator might use an electronic scorecard to fill in answers to specific questions that track progress on requirement compliance. These tools can help show whether or not a design is on track for each specific life-cycle milestone.
7.9.5.2 HSI Requirements
HSI requirements are an important HSI product. Requirements are the ultimate tool for impacting system design and performance, but they often also have cost and schedule
implications. HSI requirements ensure that the human is adequately considered during system design. HSI requirements are developed, integrated, interpreted, and verified with support from parties responsible for HSI, from systems engineering personnel, and from discipline experts in each HSI domain.
7.9.5.3 Other HSI Products
Additional HSI products may be specific to each program/project and to each domain. Products such as an acoustics noise control plan, a task analysis, human-in-the-loop verification plans, usability analysis results, radiation shielding models, habitability assessments, system
maintenance plans, and display standards are examples of domain-specific HSI products. These products contain essential data to ensure that human capabilities and limitations are adequately factored into design of the total system.
7.9.5.4 HSI Tools
HSI tools are available to contribute towards effective HSI implementation. As with products, there are tools that are specific to HSI as well as systems engineering tools that can be used for HSI purposes. HSI components for Model-Based Systems Engineering (MBSE) are currently at low levels of maturity, but this is an area where rapid improvement is anticipated.
7.9.5.4.1 HSI Key Performance Metrics
HSI key performance metrics that can be quantified and tracked throughout system development and that predict and characterize total human-plus-system performance outcomes for the
operations phase are an important HSI tool. These metrics translate into early and ongoing cost
DoD HSI Tool Resources
Additional information on available HSI tools may be found in the Department of Defense (DoD) Defense Technical Information Center’s (DTIC’s) Directory of Design Support Methods (DDSM) (Defense Technical Information Center, 2007). According to the preface of this resource: “The DDSM provides an annotated directory of human systems integration (HSI) design support tools and
techniques that have been developed by the DoD, NASA, FAA, NATO countries, academia, and private industry….The DDSM contains references to design tools or techniques that are currently available or under development. New records continue to be added as new human systems tools and techniques are developed.”
evaluation of the full life cycle of a project. Metrics allow HSI efforts to yield quantifiable and measurable impacts to system design. By tracking data such as time required for training on a system, time required for system operation and maintenance, and number of HSI issues documented in the HSI Plan, engineers can identify key areas for HSI investment. In addition, tracking the status of the HSI metrics helps to determine the program/project HSI maturity level and effectiveness as the program/project moves forward.
Examples of HSI metrics include the following:
Crew time or task efficiency (i.e., measured operational performance versus expected); Training time across design alternatives trade studies;
Total numbers of operations personnel and skill sets required;
Numbers of human interactions with major systems and subsystems; and Estimated life-cycle cost.
7.9.5.4.2 Other Tools for HSI
Section 4.3.2.2 describes use of SE tools such as functional flow block diagrams (FFBD), N- squared (N2) diagrams, and timeline analysis. Each of these tools can be applied specifically for HSI by focusing on an area of human performance or function. Output of the tools is the same as when used for a strictly hardware system, only the HSI output would be that of the human system and/or human interfaces. Outputs of tools common to systems and/or humans might be more readily integrated to serve as measures of total system performance.