Human Performance and Limitations
Human Performance and Limitations tests how the pilot’s body and mind affect flight safety: hypoxia, hyperventilation, spatial disorientation, vision, fatigue, stress, and decision-making. Questions often present a scenario and ask what is happening or what to do first.
Physiology and perception
- Hypoxia: lack of oxygen; symptoms include euphoria, headache, tingling, and poor judgement. Use supplemental oxygen when required and descend if symptoms appear.
- Hyperventilation: rapid breathing lowers CO2; symptoms can mimic hypoxia. Slow the breathing rate and reassure the patient.
- Spatial disorientation: the vestibular system can signal false climb, bank, or turn. Trust the instruments and use a stabilised scan.
- Vision: night vision is poor in the periphery; use off-centre viewing and avoid bright light before night flight.
- Fatigue, alcohol, and carbon monoxide: all degrade judgement and coordination; carbon monoxide is colourless and comes from exhaust leaks or cabin heat.
Worked example
During a night takeoff in IMC, the aircraft accelerates and the pilot feels a strong nose-up sensation. This is the somatogravic illusion: forward acceleration stimulates the otoliths like a pitch-up. The correct response is to cross-check the attitude indicator and maintain the flight director or climb attitude, not to push forward. The reasoning: the illusion is generated by acceleration, not by actual pitch, so external visual cues are absent and instruments are the only reliable reference.
Traps
Do not treat hyperventilation as hypoxia by giving oxygen without first calming the breathing, and do not trust seat-of-the-pants sensations in cloud. Alcohol and fatigue are not fixed by coffee or willpower. A pilot who feels unwell should not fly.