Human Performance and Limitations
Scope
Human performance tests how the pilot as a system performs: hypoxia, decompression, sensory illusions, fatigue, stress, vision, hearing, information processing and error. CARC questions often ask what the pilot perceives and what action is correct.
Core concepts
- Hypoxia: at FL350 time of useful consciousness is about 30–60 s; at FL400 about 15–20 s. Early signs include euphoria, poor judgement and cyanosis; supplemental oxygen is the treatment.
- Hyperventilation produces dizziness and tingling; it can be corrected by controlled slower breathing, but hypoxia must be excluded first.
- Spatial disorientation: the somatogravic illusion occurs during acceleration, which is misread as a climb; the lean is a false roll after a turn.
- Fatigue: circadian low is around 02:00–06:00; fatigue impairs monitoring and increases variability.
- Error models: slips and lapses are skill-based; mistakes are rule- or knowledge-based. Swiss-cheese defences trap errors before they become accidents.
Worked example
At night after a go-around the pilot accelerates and feels the aircraft pitching up, then pushes forward. The correct reasoning: linear acceleration stimulates the otoliths like a pitch-up; the aircraft is not climbing. The pilot should cross-check the artificial horizon and airspeed, not trust the seat-of-the-pants sensation.
Traps
Treating hyperventilation as proof of hypoxia; assuming clear thinking during hypoxia; relying on body sensations in IMC.