Human Factors
What the module tests
Human factors covers human performance, error, safety culture, communication, teamwork, fatigue, stress, situational awareness and decision-making. The exam expects you to recognise error types and the defences that reduce them, not to blame individuals.
Core rules
- A slip is a correct intention executed wrongly; a lapse is a forgotten action; a mistake is a wrong intention; a violation is a deliberate deviation from a rule.
- The SHELL model relates Software, Hardware, Environment and Liveware; the edges are where mismatch causes error.
- Fatigue reduces vigilance and slows reaction; it cannot be overcome reliably by motivation.
- Good communication uses closed-loop confirmation, especially for verbal instructions and shift handovers.
- A just culture distinguishes human error from reckless or intentional unsafe acts.
- Situational awareness has three levels: perception, comprehension and projection.
Worked example
After a 12-hour night shift, a technician intends to fit the correct bolt but picks up an identical-looking bolt of the wrong grip length and signs the task off. Classify the error and the defence. The intention was correct, so this is a slip, not a mistake. The system defences are physical segregation of dissimilar parts, colour coding, a second-person check and fatigue management. Blaming the technician alone misses the design and organisational factors that allowed the wrong part to be available.
Traps
Calling every error a mistake; treating a violation and an error as the same; assuming more training fixes fatigue; ignoring handover communication; confusing hindsight with the information available at the time.
Exam approach
Identify the intention first, then the execution. Name a specific defence rather than saying 'be more careful'.