Human Performance and Limitations
Human Performance and Limitations examines the pilot as a system component: hypoxia, hyperventilation, carbon monoxide, spatial disorientation, fatigue, stress, vision, hearing and decision-making. The exam rewards precise recognition of symptoms and the correct first action.
Physiological threats
- Hypoxia: symptoms include euphoria, impaired judgement, headache, cyanosis and poor coordination; the first action is to use supplemental oxygen and descend.
- Hyperventilation produces dizziness, tingling and confusion; it can be managed by controlled breathing, but hypoxia must be excluded.
- Carbon monoxide is odourless and causes headache, drowsiness and confusion; suspect it with cabin heat use and treat with fresh air and oxygen.
- Spatial disorientation: trust the instruments in IMC; vestibular illusions are strongest during acceleration, deceleration and bank.
Psychological and decision factors
- Fatigue degrades vigilance and increases omission errors; flight time limitations and rest are regulatory, not optional.
- Stress narrows attention; use a structured decision model and verbalise the plan.
- Alcohol, medication and illness affect fitness to fly; the CAA medical rules and the aircraft POH/operations manual set the constraints.
- Vision at night is peripheral and degraded by smoking, fatigue and bright light; avoid looking directly at a target.
Worked example
On a dark night approach over water, the runway appears higher than it is because there are few ground references - the black-hole illusion. The pilot may fly a lower approach than intended. The correct response is to use the published approach path, instrument references and glidepath guidance, not to chase the visual picture.
Traps that cost marks
- Treating hyperventilation as harmless without excluding hypoxia.
- Assuming carbon monoxide has a smell.
- Believing you can overcome spatial disorientation by “feel”.
- Ignoring the effect of fatigue on checklist discipline.