What is the TUC for 25,000 feet?

What is the TUC for 25,000 feet?

• A. 3-5 minutes
• B. 20-30 minutes
• C. 1-2 minutes
• D. 10 minutes

Answer: (A)

Time of Useful Consciousness is the period you can stay conscious after oxygen loss at altitude before hypoxia impairs your thinking and actions. At 25,000 feet, the brain loses oxygen quickly, so usable consciousness is typically about 3 to 5 minutes. That short window is why crews must don oxygen and initiate an emergency descent to a breathable altitude as soon as a depressurization event occurs. The other durations are not consistent with how rapidly hypoxia can develop at this altitude, so they don’t match the real TUC you’d expect at 25,000 feet.

Time of Useful Consciousness is the period you can stay conscious after oxygen loss at altitude before hypoxia impairs your thinking and actions. At 25,000 feet, the brain loses oxygen quickly, so usable consciousness is typically about 3 to 5 minutes. That short window is why crews must don oxygen and initiate an emergency descent to a breathable altitude as soon as a depressurization event occurs. The other durations are not consistent with how rapidly hypoxia can develop at this altitude, so they don’t match the real TUC you’d expect at 25,000 feet.