Unsafe acts are of two (2) distinct types:
- errors and
- violations
Errors arise from informational problems and fall into three (3) categories:
- skill-based slips and lapses,
- rule-based mistakes and
- knowledge-based mistakes
Violations arise from motivational factors and fall into four types:
- routine (or corner-cutting) violations,
- thrill-seeking or optimizing violations,
- necessary violations and
- exceptional violations
Everyone makes errors. They are an intrinsic part of the human condition, but certain situations are guaranteed to increase the chances that errors will be made. These are called error enforcing conditions. When they occur in the presence of dangers, there is a heightened risk of injury or damage.