Human Performance and Limitations
Human performance questions test how the body and mind behave under flight conditions and what the pilot can do about it. Organise your knowledge around the senses, the environment, and the cognitive/behavioural factors.
Key concepts: hypoxia (hypoxic, hypemic, stagnant, histotoxic), its symptoms and the value of time of useful consciousness; hyperventilation and how it mimics hypoxia; the effects of decompression and the need for immediate oxygen; spatial disorientation and the somatogravic and somatogyral illusions; the vestibular system's limits; night vision and the blind spot; noise, vibration and fatigue; circadian rhythms and jet lag; stress, workload and situational awareness; and the error chain and crew resource management (communication, leadership, assertiveness, decision-making).
Traps: assuming hypoxia always produces obvious symptoms - euphoria can mask it; confusing hyperventilation with hypoxia (both cause dizziness and tingling, but hyperventilation improves with slower breathing); and treating time of useful consciousness as a fixed value rather than one that falls with altitude.
Worked example: at FL 350, time of useful consciousness is roughly 30–60 seconds; at FL 400, roughly 15–20 seconds. A rapid decompression therefore demands immediate oxygen and an emergency descent. Rule of thumb: the higher you are, the less time you have - and the first sign of hypoxia may be a subtle change in judgement, not a dramatic symptom.