Human Performance and Limitations
The Human Performance and Limitations paper tests your ability to recognise how the pilot, not the aircraft, becomes the weak link. It covers hypoxia, fatigue, stress, vision, hearing, spatial disorientation, decision-making, error models and crew resource management.
Physiology
Hypoxia begins with euphoria, headache and poor judgement before the pilot notices. Smoking, alcohol and some medicines increase susceptibility. Hyperventilation produces dizziness and tingling but can be managed by controlled breathing. Carbon monoxide from a faulty heater causes headache and confusion; suspect it if symptoms clear after opening vents. Fatigue slows checklist use and increases omission errors.
Psychology and decision-making
Use IMSAFE (Illness, Medication, Stress, Alcohol, Fatigue, Eating) before flight. Alcohol and drugs, including some over-the-counter remedies, are incompatible with flying; know the MCAR limits and the bottle-to-throttle rule. The SHELL model shows liveware at the centre; the Swiss-cheese model shows latent and active failures lining up. Threat and error management means anticipating, trapping and recovering from errors.
Worked example
After a long day, a pilot feels irritable and skips the before-landing checklist; the gear warning sounds on final. The correct reasoning is not 'I can handle it' but 'fatigue has degraded my monitoring'. Go around, complete the checklist, land and do not continue the planned second leg. The missed checklist is an active error; the long duty day is a latent condition.
Traps
Assuming hypoxia only occurs at high altitude; confusing hyperventilation with hypoxia; flying with a cold and blocked sinuses; treating eight hours since last drink as the only test; and ignoring dehydration in tropical heat.