Human Performance and Limitations
This domain rewards understanding of how the pilot as a system fails. Cover the senses used in flight (vision, hearing, vestibular system), spatial disorientation, hypoxia and hyperventilation, decompression, carbon monoxide, fatigue, stress, workload, decision-making, and the psychology of error. Know the difference between a slip (wrong action) and a mistake (wrong intention), and the SHELL and Reason models at a conceptual level.
Key physiological facts: night vision is dominated by rods, which are poor at detail and colour and slow to adapt; use off-centre viewing at night. The vestibular system cannot distinguish sustained acceleration from gravity, which is why spatial disorientation occurs in cloud without instruments. Hypoxia symptoms are insidious - euphoria, poor judgement, cyanosis - and time of useful consciousness falls rapidly with altitude. Hyperventilation produces dizziness and tingling and can mimic hypoxia; the treatment is controlled breathing and, if in doubt at altitude, assume hypoxia and use oxygen.
Traps: candidates confuse the effects of alcohol and fatigue, forget that CO poisoning causes headache and cherry-red lips only late, and misremember the hypoxia onset altitudes. Worked example of a rule of thumb: at 10,000 ft time of useful consciousness is roughly 1 hour, at 25,000 ft about 3–5 minutes, and at 40,000 ft around 15–20 seconds - use these to reason about why supplemental oxygen rules exist. For decision-making, use the DECIDE model: Detect, Estimate, Choose, Identify, Do, Evaluate.