Recognising symptoms — the personal signature
Hypoxia presents differently in each person. Common symptoms:
| Category | Examples |
|---|---|
| Sensory | Blurred vision, tunnel vision, reduced colour perception, tinnitus |
| Cognitive | Impaired concentration, slow reaction, poor decisions, euphoria |
| Motor | Coordination loss, tremor, difficulty writing |
| Visible | Cyanosis (blue lips/nails), tachypnoea (rapid breathing), sweating or shivering |
| Subjective | Headache, dizziness, nausea, fatigue, tingling |
Tip: Chamber training (in Germany e.g. DLR Aviation Medicine Cologne) lets every pilot know their own signature — strongly recommended for mountain pilots.
Recovery (sequence matters)
- Don oxygen (if available, with 100 % setting).
- Descend to < 10 000 ft cabin altitude — fastest path to recovery.
- Slow breathing and breathe deeply (prevents secondary hyperventilation).
- If CO poisoning is suspected, also: fresh air (open cabin vents, heat off), land as soon as possible.
Prevention
- Pulse oximeter in cockpit (real-time SpO₂, battery-powered).
- Be a non-smoker — smokers have a "altitude bonus" of ~5 000 ft (3–5 % of Hb blocked by CO).
- Avoid exertion at altitude.
- Stay hydrated.
- Use oxygen prophylactically from 10 000 ft on longer flights.
Suspect: hypoxia or hyperventilation?
Symptoms overlap strongly. Rule of thumb: assume hypoxia first (more dangerous) — descend and use oxygen. Hyperventilation can be excluded on the ground later.