At what cabin elevation do supplemental passenger oxygen masks automatically actuate?

Supplemental passenger oxygen masks automatically actuate when the cabin altitude reaches 14,000 feet, plus or minus 500 feet. This is an important safety measure designed to protect passengers in the event of cabin depressurization. At this altitude, the partial pressure of oxygen decreases to a level where it may not be sufficient to meet the physiological needs of the human body, particularly during rapid descent or emergencies. Therefore, the activation of the oxygen masks ensures that passengers can breathe comfortably until the aircraft descends to a safer, breathable altitude.

This threshold is established based on regulations and safety standards to ensure passenger safety in scenarios where cabin pressure is lost or significantly altered. The design of the aircraft's oxygen system is critical for maintaining a safe environment at higher altitudes, making the specified altitude for automatic actuation a key element in modern aviation safety procedures.