Aeromedical factorsQuestion 716 of 934

What does the term time of useful consciousness describe?

  1. The time that a pilot needs to recover after using oxygen
  2. The time that a portable oxygen tank lasts at altitude
  3. The time to make rational decisions without supplemental oxygen
  4. The time before the pilot feels the first symptom of hypoxia
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Correct answer: The time to make rational decisions without supplemental oxygen

It is the maximum time to make and carry out life-saving decisions at a given altitude without oxygen.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 17: Aeromedical Factors — Treatment of Hypoxia, page 426

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Questions last reviewed: 18 October 2026