Flight personnel shall not perform flight duties for 12 hours after exposure to LPC in excess of how many feet?

• A. 30,000 feet
• B. 20,000 feet
• C. 40,000 feet
• D. 50,000 feet

Answer: (A)

Exposure to a low-pressure environment in an altitude chamber can cause dissolved inert gas, like nitrogen, to come out of solution when normal pressure is restored. This creates a risk of decompression sickness if the body hasn’t fully off-gassed before resuming flight duties. The practice is to impose a 12-hour stand-down after an LPC exposure that simulates or exceeds 30,000 feet because that level markedly increases the likelihood of gas bubbles forming and symptoms developing. Waiting allows any bubbles to resolve and reduces the chance of in-flight physiological issues. Exposures below this threshold don’t obligate the 12-hour rest in the same way, and higher simulated altitudes are managed with the same rule because the 30,000-foot mark represents the point at which the risk becomes significant.