Varieties of unsafe acts and the human factor
| Intent | Type of error | Aetiology | Potential promoting conditions |
| Unintended | Slips in attention | Intrusions Omissions | Hostile working environment Workload |
| Misordering | Lack of protocols and guidelines | ||
| Lapse in memory | Losing one's place | Poor machine or tool to person interface | |
| Forgetting items | Monotony and boredom | ||
| Mistake | Rule based | Poor experience and skill mix of staff | |
| Knowledge based | Misperception of risks | ||
| Deliberate | Mistake | Rule based | Perceived licence to break rules |
| Knowledge based | Conflict or poor morale which impairs “asking for help” | ||
| Violation | Short cuts | Ambiguous or apparently meaningless rules | |
| Optimising for some goal unsafely | Belief that bad outcomes do not happen | ||
| One off breaches | Culture that encourages risk taking | ||
| Sabotage | Poor supervision and checking |
Adapted from Reason.1 ,15