Human Performance and Limitations
Human performance questions test whether you can recognise and manage the pilot as a system component: hypoxia, spatial disorientation, fatigue, stress and workload in the IFR environment, including single-pilot operations.
Hypoxia and oxygen
At FL350 the time of useful consciousness is only 30–60 seconds; at FL400 it is 15–20 seconds. Symptoms are insidious: euphoria, tingling, poor judgement and visual dimming. Hyperventilation causes similar tingling and dizziness but improves with slowed breathing, whereas hypoxia does not. Use supplemental oxygen as required and avoid prolonged exposure above 10,000 ft in unpressurised aircraft.
Spatial disorientation
The somatogravic illusion during acceleration, such as a go-around, feels like a pitch-up and tempts a push-over. The somatogyral illusion follows prolonged turns, and the leans follow a slow roll. Black-hole approaches over dark terrain increase the risk. Trust the attitude indicator and cross-check it.
Fatigue, stress and decisions
Circadian lows, long duty days, night IFR, high-altitude aerodromes and single-pilot workload all degrade performance. Use IMSAFE, set personal minima, brief threats and avoid mode confusion from over-trusting automation.
Worked example
After a night go-around at JKIA, acceleration makes you feel nose-high. If you push forward, you descend. Recognise the somatogravic illusion, hold the attitude on the ADI and fly the published missed approach on instruments.
Marks-losing traps
Mistaking hypoxia for hyperventilation; ignoring carbon monoxide; pressing on with fatigue; over-trusting automation; failing to cross-check during high-workload phases.