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The Time of Useful Consciousness..
  • A
    is the same amount of time for every person.
  • B
    is independent of physical and psychological pressure.
  • C
    varies individually and is independent of altitude.
  • D
    varies individually and depends on cabin pressure altitude.


The time of useful consciousness refers to the time available to individuals to perform their tasks, after they have been deprived of oxygen, but are still aware of their environment and capable of controlling their actions.
It is important for the cabin crew to realize that the time of useful consciousness is different for each individual, and depends on the:
  • Altitude;
  • Individual’s state of health;
  • Amount of activity.

Relationship between Altitude and TUC:
Altitude TUC
40 000 ft 15 – 20 s
35 000 ft 30 – 90 s
30 000 ft 1 – 2 min
25 000 ft 2 – 3 min
20 000 ft 30 min

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  • United Kingdom