In Reason’s Swiss Cheese model, there are four “slices “or tiers of human error potential, divided into two sections: an “active” layer and “Latent Factors”: preconditions, Supervision, and Organization. The goal of the Human Factors Analysis and Classification System (HFACS) is to understand human factors throughout the system rather than stopping at the operator.
Most mishaps can be connected to human events at NASA, from 2010-2015, human events and conditions totaled 79% of causal factors identified in its mishaps and close calls. Consequently, NASA now requires the participation of a Human Factors Investigator in Type A & B mishaps and High Visibility Close Calls.
These are Influences or Factors closely tied to the mishap and described as actions or inactions that result in a mishap. There are four (4) areas in this active layer, and these are:
- Decision/judgment errors, AKA “An honest mistake.”
- They also can be in the form of skill-based errors, which are events that occur when a specific action is performed in a manner that leads to a mishap.
- Additionally, Perception Errors are influences or factors when misperception of an object, threat, or situation results in a human event.
- Finally, although we don’t like to admit it, Violations are those factors when the individual intentionally breaks the rules and instructions.
This is just the first area an analysis or investigation should examine. But how did we get here? What performance-shaping factors were present? We must go beyond the operator level, and to do that, we need to examine the Latent Factors.
This first section of the Latent Factors is by far the largest. It concerns the ENVIRONMENTAL FACTORS, which are factors that affect the practices, conditions, and actions or inactions of an individual or team. There are three (3) of these environs:
- Physical,
- Technological, and
- Space.
Also in this section is PERSONNEL FACTORS, which is when teamwork or self-imposed stress affects practices, conditions, or actions of performance. Two subcategories reside here:
- Communication and
- Self-Imposed Stress
which are factors that affect the Team or the individual’s readiness or ability to perform.
Lastly, five (5) INDIVIDUAL FACTORS these are factors of cognitive psycho-behavioral, adverse physical state, or physical/mental limitations that affect practices, conditions, or actions of individuals. These are divided into
- Awareness Cognitive Factors,
- Adverse Psychological,
- Adverse Physiological,
- Medical / Mental and
- Perception
But how did these conditions come to be?
This second part of Latent Factors is when the methods, decisions or policies of the supervisory chain of command directly affect practices, conditions, or individual actions and result in human events or an unsafe situation.
In this section, there are four (4) categories or buckets:
- Failure to Correct a Known Problem,
- Inadequate Supervision,
- Planned Inappropriate Operations, and
- Violations.
Yes, Supervisors are people, too, and can make mistakes. These can stem from inadequate training, pressure from above or below, doing too much with too little, or knowingly bending the rules to accomplish the mission.
What Organizational influences were present to affect Supervision in this way?
This final piece of the Latent Factors is Organizational. This is Center Management: Policy, Processes, Resources, and Facilities …its Culture. This level describes the methods, decisions, or policies of an organization and how they affect both supervisory and individual task and mission accomplishment.
This level is divided into three buckets:
- Culture / Climate: Attitudes, beliefs, or values that are shared, or the perception of stress and or morale within an organization.
- Processes: Are factors when organizational processes, procedures, risk management and oversight negatively impact operations.
- And of course, Resources: are factors when the staffing, facilities or products an organization needs to accomplish a mission are inadequate or improper and this condition reduces system safety or increases operational risk.