Human Performance and Limitations
This domain examines human physiology and psychology in flight: hypoxia, hyperventilation, spatial disorientation, illusions, fatigue, stress, vision, hearing and crew resource management. Questions ask you to recognise a condition and choose the safest response.
Physiology
- Hypoxia: lack of oxygen to tissues; early signs include euphoria, poor judgement, tingling and cyanosis. Correct with 100% oxygen and descent.
- Hyperventilation: overbreathing lowers CO2; dizziness and tingling mimic hypoxia. If unsure, give oxygen and slow the breathing rate.
- Carbon monoxide is odourless; suspect it with headache and nausea, especially with cabin heat on.
- Spatial disorientation: trust the instruments, not sensations.
Psychology and performance
- Fatigue degrades attention and increases error; rest is the only real cure.
- Stress narrows attention; use prioritisation and checklists.
- CRM and threat and error management: brief threats, assign roles, speak up, monitor.
Worked example
On a dark night approach with no visual horizon, a pilot sees the runway lights and believes the aircraft is too high, then descends below the approach path. This is the black-hole illusion: a bright runway with no surrounding cues appears closer and higher. The correct response is to maintain the published glidepath and instrument indications, not to chase the visual picture.
Traps
- Treating hyperventilation as hypoxia and delaying descent.
- Believing you can push through fatigue.
- Using alcohol or medication against KCARs limits.
- Failing to recognise that spatial disorientation worsens with rapid head movement.
- Assuming a pilot's subjective picture is reliable in poor visual cues.