In gradual/slow decompression, what may a person experience?

• A. Not be aware of not getting enough oxygen; always watch for signs of hypoxia.
• B. Immediate loss of consciousness.
• C. Sudden paralysis.
• D. No effects.

Answer: (A)

In gradual decompression, the oxygen level in the cabin falls slowly, so the body and brain have time to adapt, and a person may not notice they’re not getting enough oxygen. Because the change is gradual, the signs of hypoxia can be subtle or delayed, leading someone to feel mostly normal even as their cognitive function, judgment, and alertness decline. That’s why the best answer highlights that a person may not be aware of the lack of oxygen and should be vigilant for hypoxia symptoms like headache, dizziness, fatigue, impaired concentration, or shortness of breath, so they can respond promptly with oxygen or descent. The other scenarios—immediate loss of consciousness, sudden paralysis, or no effects—don’t fit gradual decompression, where symptoms tend to develop gradually rather than abruptly and are often not immediately obvious.