In Reason's Swiss Cheese Model, the events and conditions that contributed to an error's occurrence are called

• A. Active failures
• B. Systemic faults
• C. Preconditions
• D. Latent conditions

Answer: (D)

In this model, errors don’t come from a single mistake in isolation; they arise when weaknesses in the system create holes in multiple defenses that align at the same time. The events and conditions that contribute to an error are latent conditions—systemic weaknesses built into design, procedures, culture, supervision, and maintenance. These factors can sit quietly in the background, yet they shape how people perform and how defenses respond. When an active failure by a person occurs—such as a slip or lapse—the holes in the layers line up, permitting the error to reach fruition. Active failures are the immediate human actions, not the underlying system factors. Preconitions describe enabling circumstances for unsafe acts, but the broad, umbrella term for these underlying, persistent system factors is latent conditions.