Human Performance and Limitations
Human Performance and Limitations
This domain examines how the pilot’s body and mind affect flight safety: hypoxia, hyperventilation, decompression, disorientation, fatigue, vision, hearing, decision-making and crew resource management.
Physiology. Hypoxia is insufficient oxygen at the tissues; symptoms include euphoria, poor judgement, cyanosis and headache. Time of useful consciousness falls rapidly with altitude. Hyperventilation causes dizziness and tingling but can be corrected by controlled breathing; hypoxia needs oxygen and descent. Carbon monoxide is odourless and causes headache and confusion. Spatial disorientation arises when visual cues conflict with vestibular inputs, especially at night or in cloud.
Psychology and CRM. Fatigue degrades vigilance and reaction time; circadian lows occur in the early morning and mid-afternoon. Use IMSAFE before flight. Good CRM includes briefings, workload sharing, assertiveness, situational awareness and closed-loop communication. Decision-making models such as DECIDE or FOR-DEC help under stress.
Worked example
On a dark night approach over water, a pilot sees the runway lights higher than expected and flies a lower approach. The black-hole illusion makes the runway appear farther away and higher, so the pilot descends too low. The defence is to use the glideslope or PAPI and instrument references, not visual judgement alone.
Traps
Do not treat hyperventilation with more oxygen without considering hypoxia. Do not assume “I feel fine” means no hypoxia. Alcohol, drugs and fatigue are cumulative; a legal limit is not a fitness standard.