Human Performance and Limitations
What this domain tests
Human Performance and Limitations tests hypoxia, decompression, spatial disorientation, fatigue, stress, vision and hearing, and crew resource management. Questions are often scenario-based: what is happening and what should the pilot do?
Core rules
- Hypoxia: at FL 350, time of useful consciousness is roughly 30-60 seconds after rapid decompression. Symptoms include euphoria, tingling and poor judgement; the remedy is oxygen and descent.
- Hyperventilation can mimic hypoxia; if in doubt, use 100% oxygen and control breathing rate.
- Spatial disorientation: the somatogravic illusion during acceleration feels like a climb; the black-hole approach makes a shallow approach look correct. Trust the instruments.
- Fatigue: circadian low points occur around 03:00-05:00 and 15:00-17:00; cumulative sleep debt impairs performance more than acute sleep loss.
- CRM: brief, monitor and cross-check; assertiveness and closed-loop communication reduce error.
Worked example
On climb-out at night, the pilot feels a strong pitch-up sensation after acceleration. The somatogravic illusion is caused by linear acceleration stimulating the otoliths. The correct response is to cross-check the artificial horizon and airspeed, not to push over from sensation alone.
Traps
Assuming oxygen is only needed above 10,000 ft; forgetting that decompression can cause lung damage if the breath is held; confusing hypoxia with hyperventilation; attributing fatigue errors to lack of motivation. The Swiss-cheese model is about defences, not blame.
Key habit
For any HPL scenario, identify the sensory or cognitive limitation first, then the instrument or procedure that overrides it.