Flight personnel shall not perform flight duties for _____ hours after exposure to low pressure chamber flight in excess of 30,000 feet.

• A. 6 hours
• B. 12 hours
• C. 18 hours
• D. 24 hours

Answer: (B)

When flight personnel are exposed to a low-pressure environment above 30,000 feet, nitrogen gas can come out of solution in the body's tissues. If they resume flight duties too soon, those gas bubbles can grow or cause decompression sickness during subsequent altitude changes or stress of flight. The required rest period of twelve hours gives the body time to off-gas safely and reduces the risk of symptoms or impaired performance in the air. Six hours would be too short to allow meaningful off-gassing, while eighteen or twenty-four hours would be longer than necessary for typical exposures and would unnecessarily delay operations. If no symptoms appear, twelve hours is the standard safety window to ensure safe re-entry into flight duties after such exposure.