Human Performance and Limitations
What the exam tests
This domain examines hypoxia, hyperventilation, decompression, spatial disorientation, sensory illusions, fatigue, stress, vision, hearing, medication and crew decision-making. Questions often ask for the first correct recognition or response rather than a diagnosis.
Core rules
- Hypoxia impairs judgement and vision before the pilot notices; symptoms include euphoria, tingling and poor coordination. Use supplemental oxygen and descend.
- Hyperventilation causes dizziness and tingling from excessive breathing; it can mimic hypoxia. Treat suspected hypoxia with oxygen and descent first.
- Spatial disorientation is best countered by trusting flight instruments and avoiding sudden head movements.
- The somatogravic illusion occurs during acceleration or go-around: acceleration is misread as pitch-up, tempting the pilot to push forward.
- Fatigue and stress narrow attention and increase omission errors; use checklists, prioritise and share workload.
Worked example
During a go-around at night, the pilot feels the aircraft pitching up steeply and pushes forward. Reasoning: acceleration along the runway axis stimulates the otoliths and can feel like pitch-up. The correct response is to cross-check the attitude indicator and airspeed, establish the required pitch attitude on instruments, and ignore the false sensation.
Traps
Treating hyperventilation as harmless while hypoxia worsens; assuming euphoria means you are fine; relying on bodily sensations in IMC; taking medication without checking fitness; ignoring carbon monoxide as a cause of headache and confusion.