At what pressure altitude will the crew oxygen masks provide 100% oxygen regardless of switch position?

• A. 20,000 Feet
• B. 25,000 Feet
• C. 30,000 Feet
• D. 35,000 Feet

Answer: (C)

The important idea is how the crew oxygen system is designed to protect you at very high altitude. As you climb, the air gets thinner and the risk of hypoxia increases. To ensure the crew remains protected, the system is set up so that above a certain pressure altitude the masks deliver 100% oxygen automatically, regardless of the mask switch setting. On the CRJ-550, that threshold is 30,000 feet. So once you reach 30,000 feet, the crew masks provide 100% oxygen no matter what position the switch is in, ensuring immediate full protection if pressurization is lost or the switch is not set for a higher flow. Below that altitude, the switch position can influence the oxygen delivery, but above it, 100% oxygen is guaranteed to the crew.