What is the time of useful consciousness at 15,000 feet?

• A. 30 minutes
• B. 2 hours
• C. 5 minutes
• D. 1 hour

Answer: (A)

Time of useful consciousness is the period after hypoxia starts during which you can still perform meaningful tasks. At 15,000 feet, the brain receives less oxygen, so your performance declined but you’re not immediately unconscious. The standard estimate for unoxygenated conditions at this altitude is about 30 minutes, which is the window you have to take action—don a mask, descend, or implement other emergency procedures. Using supplemental oxygen greatly extends this window by increasing oxygen delivery to the brain, giving you more time to respond. This 30-minute figure is a common benchmark used in aviation training for depressurization at this altitude.