Human Performance and Limitations
This domain tests the pilot as a system: hypoxia, hyperventilation, spatial disorientation, fatigue, stress, vision, hearing, alcohol/drugs, medical fitness and decision-making. Helicopter work adds vibration, noise, confined cockpits and low-level visual illusions.
Core threats
Hypoxia reduces oxygen to the brain; early signs include euphoria, headache and poor judgement. Hyperventilation causes dizziness and tingling but can be managed by controlled breathing. Carbon monoxide is odourless and causes headache and confusion. Spatial disorientation arises when visual cues conflict with vestibular senses; black-hole approach and somatogravic illusions are relevant at night. Fatigue slows reaction and increases error; dehydration and stress worsen it.
Fitness and decision-making
No alcohol or impairing drugs; follow medical restrictions and report changes. Use CRM: brief passengers, assign tasks, call ‘go-around’ early and avoid get-there-itis.
Worked example
A pilot at 10,000 ft cabin altitude develops headache, tingling and blurred vision. Pulse oximeter shows 88%. The pilot should suspect hypoxia, descend, use oxygen if available and land if symptoms persist. The reasoning: SpO2 below normal plus altitude exposure makes hypoxia more likely than hyperventilation; do not delay descent to ‘test’ fitness.
Traps
Treating hyperventilation and hypoxia as the same; ignoring CO risk from cabin heat; pressing on with fatigue; and assuming night visual illusions disappear with experience.