The Value of HSI

The application of human systems integration (HSI) throughout a project results in improved system performance, reduced lifecycle cost, reduced development risk, and no increase in development cost when executed effectively.

HSI is a systems engineering technical management approach which ensures that the human is considered a sub-system on par with hardware and software subsystems by integrating the efforts of the HSI specialties: Manpower and personnel planning, training, human factors engineering, human survivability, habitability, environment, safety, and occupational health.

Projects often undervalue these domains, viewing them as a box to be checked at the end of the effort. Issues discovered at this point are often very costly to correct1. If an issue completely fails a major requirement, it may be ‘fixed’ with a suboptimal kludge. Any issues which don’t impede system acceptance won’t be fixed at all, no matter how much they reduce operational effectiveness.

HSI increases the visibility and consideration of these specialties in the systems engineering program. This ultimately benefits the contractor and the customer.

The goal [of HSI] will be to optimize total system performance and total ownership costs, while ensuring that the system is designed, operated, and maintained to effectively provide the user with the ability to complete their mission.

DoD Instruction 5000.02


From the customer’s perspective, HSI ensures that oft-neglected aspects of lifecycle cost such as manpower and personnel are considered early in the development phase, potentially saving a lot of money during operation. Habitability is another such factor, especially in systems which are occupied for long durations, as high morale and quality rest result in favorable performance.

From the contractor’s perspective, HSI offers risk reduction. Programs without HSI may find that their solution meets the system requirements but fails to fully meet the mission needs when used by actual humans. In cases where human-related requirements are well-defined, a lack of HSI could result in failing contracted system requirements outright.

Both the customer and the contractor benefit when the system performs well. HSI helps to achieve desired system performance, including mission effectiveness and reduced error.

Involvement of the HSI domain specialists at every phase of the project ensures that human-related aspects are fully considered in requirements decomposition, tradeoffs, modeling, design and development, evaluation, and system support processes.


The best part about HSI is that it can be cost-neutral for both dollars and schedule.

HSI rarely has a negative schedule impact because HSI-related activities occur in parallel with other efforts. Adding a human systems integrator to the systems engineering team may add some marginal cost, up to three full-time integrators for an extremely large project. A smaller project may even split one person between HSI and other SE duties. This small cost more than pays for itself during the life of the project.

A large part of the HSI effort is simply ensuring that the specialty resources already in the budget are plugged in to the appropriate engineering processes. For example, when the integrator notices a trade study that may have a safety impact, they make sure the safety engineer is added to the trade study team. The safety impact will have already been assessed and incorporated when the trade study is presented at the review board, allowing the analysis to be passed the first time. If safety wasn’t included originally, sending the trade study back for a safety analysis would cause a budgetary delay and potentially add cost, especially if the results significantly affect the study’s findings.

HSI-proposed work, such as trade studies specifically addressing HSI domain factors, may also add some dollar cost to the project. These pay for themselves by improving the suitability of the system and reducing risk. Going back to the defect fixing curve, it is much more cost-effective to conduct these studies early on and incorporate the findings into the engineering effort than to have to fix major shortcomings later on.

Finally, HSI can often identify opportunities for additional work to improve one or more domain considerations. For example, a study on training approaches may lead to a supplemental contract to develop training resources for the system, benefiting the contractor through new work and the customer through more effective and integrated training.


In short, HSI is a natural part of the systems engineering process. It adds minimal up-front cost for significant benefits and cost savings.

Optimizing the system for performance and lifecycle cost benefits the customer. Ensuring early consideration of HSI factors reduces the risk of costly rework to the contractor. Delivering a system which is mission effective with reasonable lifecycle costs benefits everyone.

How has HSI benefited your project? Can HSI achieve more value? How can HSI go wrong? Let me know in the comments or see the about page if you’d like to do a guest post.


  1. I assume every engineer is familiar with Boehm’s classic “cost to fix defects curve”… if you’re not, something search it.