Process

The human factors engineering process essentially represents an adaptation of the system engineering process. As such, the HFE process must be: requirements-driven, standardized and formalized, an influence on design, and integrative.

HFE design concepts and criteria are developed and evaluated based on a comprehensive and complete identification, analysis and integration of requirements, including user requirements, performance requirements, information/knowledge requirements, decision requirements, functional requirements, task requirements, communication requirements, quality of life requirements, and human-machine interface design requirements.

The thrust of the HFE design process is to present an approach which is generic to all system development efforts while at the same time being able to be tailored to the specific constraints of each individual program. The characteristics of the HFE design process which impact its ability to be standardized and formalized include the extent to which it is: comprehensive and complete, accurate, internally consistent, compatible with the capabilities of its users, in compliance with the governing specifications and standards, usable for its intended purpose, and effective in enabling HFE personnel to develop design concepts and criteria, conduct analyses, and perform evaluations.

The way in which the HFE design process seeks to ensure that human performance concerns will influence system design is to provide an approach for getting HFE into system development early in the development process. The HFE process requires evaluation of human performance aspects of predecessor systems prior to formal system initiation as an input to early system design concepts.

The HFE process is integrative at several levels. The individual steps of the process are integrated among themselves. The steps of the process are integrated with human performance data bases and HFE tools. Finally, the entire HFE process must be integrated with the products, activities and milestones of the system acquisition process.

A central HFE issue in system design involves establishing and defining the role of the human in the system. Determination of the role of the human begins with an allocation of system functions to human or machine performance, but must proceed well beyond the simple function allocation approach. An allocation of functions results in decisions as to which tasks should be performed by man and which should be performed by machine. It is based on an assessment of the differential capabilities and limitations of man and machine in terms of the requirements associated with a specific function. The problem with limiting HFE analysis to the allocation of functions is the underlying and erroneous assumption that functions can be clearly and totally assigned to human or machine, that no interactions among human and machine are required for specific functions, and that the human has no role in automated functions. The increasing need for interactive dialogues between human operator and computer in many automated systems underlines the requirement to consider the interactions between human and machine where few operations are either purely manual or totally automated, and most are "semi-automatic". The role of the human in what are truly automated operations must also be acknowledged. While this role is different than it would be in a manual operation, the human does play a real role in automated operations, as activator, monitor, manager, and, at times, an intervener, taking over control from the automated process. With these considerations in mind, it is apparent that the focus of the HFE process must be on the determination of the role of the human in the system, rather than merely allocating functions to human or machine performance.