Human Performance and Limitations
The human in the loop
This domain examines how the pilot's body and mind behave in flight. Understand hypoxia (hypoxic, hypemic, stagnant, histotoxic), its symptoms and the time of useful consciousness at altitude; hyperventilation and how it mimics hypoxia; decompression sickness; and the effects of acceleration and spatial disorientation. Sensory illusions - somatogravic, somatogyral, the leans, false horizon - are frequent question topics because they explain why instrument reference matters.
Vision and hearing: know the blind spot, night vision and the importance of off-centre viewing, and how noise and vibration affect fatigue. Cognition: understand workload, situational awareness, decision-making models, and the difference between an error and a violation. Fatigue, stress and circadian rhythm strongly influence performance.
Traps: confusing hypoxia with hyperventilation (both cause dizziness and tingling; hypoxia is treated with oxygen, hyperventilation by controlled breathing); assuming time of useful consciousness is fixed (it falls rapidly with altitude); and forgetting that alcohol, medication and dehydration compound altitude effects.
Rule of thumb
For any physiology question, ask: what is the cause, what does the pilot feel, and what is the correct action? Hypoxia → oxygen and descend. Hyperventilation → slow the breathing rate. Spatial disorientation → trust the instruments, not sensations.