Human Performance and Limitations
The human in the loop
Human performance questions test whether the candidate understands how pilots actually fail: fatigue, hypoxia, spatial disorientation, sensory illusions, stress, workload, and communication breakdown. The underlying model is information processing - sensation, perception, decision, action - with limited attention and working memory. Candidates should know the difference between an error, a violation, and a slip or lapse, and understand the SHELL and Reason models at a conceptual level.
Key phenomena
Hypoxia: symptoms are insidious, and euphoria can mask them; time of useful consciousness falls rapidly with altitude. Spatial disorientation: somatogravic illusion (acceleration feels like climb), somatogyral illusion (spin), and the leans. Visual illusions on approach: black hole effect (too low), runway width illusion (too high or too low), and sloping terrain. Fatigue: acute versus chronic, and the role of circadian rhythm.
Traps in questions
- Confusing the leans with the somatogravic illusion.
- Assuming a pilot can reliably detect hypoxia without a pulse oximeter.
- Treating stress as always harmful - some stress improves performance, but excessive stress degrades it.
- Forgetting that crew resource management includes briefings, callouts, and challenge-response.
Worked rule of thumb
When a scenario describes a pilot who "feels fine" but is making small errors at altitude, suspect hypoxia before fatigue. The rule: unexplained euphoria plus degraded performance at altitude equals oxygen first, analysis second.
Study approach
For each illusion, write the maneuver that provokes it and the correct instrument response: trust the instruments, not the sensation.