Friday, October 30, 2026 · Captain's Challenge
The Captain's Challenge.
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Time of useful consciousness (TUC) at 25,000 feet without supplemental oxygen is approximately:
The answer
22 to 3 minutes
Explanation
TP 13312 (Handbook for Civil Aviation Medical Examiners), Figure 8 — Times of Useful Consciousness: 25,000 ft, 2 – 3 minutes. The time falls quickly with altitude: 5 – 12 minutes at 20,000 ft, 45 – 75 seconds at 30,000 ft and 10 – 30 seconds at 40,000 ft.
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