What is the trigger for supplying oxygen to the passenger outlets when the Pax O2 switch is auto?

• A. Cabin altitude exceeds 13,500 feet
• B. Cabin altitude exceeds 15,000 feet
• C. Cabin altitude exceeds 12,000 feet
• D. Cabin altitude exceeds 10,000 feet

Answer: (A)

In auto mode, the passenger oxygen system is controlled by a cabin altitude sensor. When cabin altitude rises above 13,500 feet, the system automatically opens the passenger outlets to deliver oxygen to occupants. This threshold is chosen to ensure oxygen is available during depressurization before hypoxia becomes a risk, while still conserving oxygen when cruising at lower altitudes. The other numbers don’t correspond to the auto trigger for this aircraft's Pax O2 system.