Human Performance and Limitations
Human Performance and Limitations tests how pilot physiology, psychology and teamwork affect safety. The CPL exam expects practical recognition of hypoxia, decompression, spatial disorientation, fatigue, stress and CRM.
Physiology
- Hypoxia: symptoms include euphoria, tingling, blurred vision, poor judgement. Time of useful consciousness at FL350 is roughly 30–60 seconds after rapid decompression.
- Decompression: don oxygen mask first, then check the other crew member; descend to below 10,000 ft or the lowest safe level.
- Spatial disorientation: somatogravic illusion in acceleration, leans after rolling out, and the false horizon. Trust instruments.
Psychology and teamwork
- Fatigue degrades vigilance and decision-making more than skill; controlled rest and workload management help.
- Stress narrows attention; use checklists and prioritise aviate, navigate, communicate.
- CRM: brief, assign roles, speak up, and close the loop in communication.
Worked example
At FL350 a rapid decompression occurs. Put on the oxygen mask first, establish communication, check the other pilot, then initiate an emergency descent. Do not delay the descent to troubleshoot the pressurisation system; hypoxia will degrade your ability before the cause is found.
Traps
Confusing hyperventilation with hypoxia (hyperventilation improves with slower breathing, hypoxia does not); assuming you can overcome spatial disorientation by feel; treating fatigue as a motivation issue; forgetting to include the cabin in decompression decisions.