Human Performance and Limitations
Human Performance and Limitations
This domain covers the pilot as a system: hypoxia, hyperventilation, spatial disorientation, fatigue, stress, vision, decision-making and crew resource management. The exam tests recognition and practical response, not medical diagnosis.
Core concepts
- Hypoxia: insufficient oxygen to tissues. Symptoms include euphoria, headache, impaired judgement and cyanosis. At altitude, use supplemental oxygen per rules and descend if symptoms occur.
- Hyperventilation can mimic hypoxia; both cause dizziness and tingling. If uncertain, treat as hypoxia and descend.
- Spatial disorientation: trust the instruments, not sensations. Somatogravic illusion during acceleration feels like a nose-up pitch.
- Fatigue and stress degrade scanning, radio work and decision-making. Recognise cumulative fatigue before flight; do not “push through.”
- Vision at night: use off-centre viewing; avoid bright white light; allow dark adaptation.
- CRM/ADM: verbalise threats, set personal minimums, and use a decision model such as PAUSE or DECIDE.
Worked example
At night after a go-around, the pilot accelerates and feels the aircraft pitching up, so pushes forward. Without a visible horizon, this is likely somatogravic illusion: acceleration stimulates the otoliths like a pitch-up. The correct response is to cross-check airspeed, attitude indicator and altimeter, maintain the flight path, and ignore the false sensation. Pushing forward could cause a descent into terrain.
Traps that cost marks
Self-medicating fatigue with caffeine; assuming “I feel fine” means fit to fly; failing to recognise carbon monoxide as a cause of headache and confusion; and using night vision techniques in daylight without understanding their limits.