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: