The automatic closure of the passenger O2 mask valve after mask deployment occurs at what altitude?

The automatic closure of the passenger O2 mask valve after mask deployment occurs at an altitude of approximately 9,000 feet, plus or minus 1,000 feet. This altitude range is crucial because it aligns with regulations and safety measures regarding supplemental oxygen use for passengers in case of cabin depressurization.

At altitudes above 9,000 feet, the risk of hypoxia increases, making the provision of oxygen masks for passengers essential for their safety and well-being. The design of the mask system ensures that the oxygen supply is activated at this altitude to provide immediate assistance. By automating the closure valve at this specific altitude, the system ensures that oxygen is only provided when necessary, conserving resources and preventing unnecessary depletion of the oxygen supply.

Understanding the operational parameters of the oxygen system is essential for the crew in ensuring passenger safety and effectively managing in-flight emergencies. Thus, recognizing that the closure occurs around 9,000 feet situates the emergency oxygen deployment process within the operational norms established for high-altitude flight safety.