How is the oxygen system used by crew and passengers?

• A. It provides breathable air during depressurization; masks deploy automatically to crew and passengers and can be manually engaged as needed
• B. It is used only by crew
• C. It is used only on the ground
• D. Oxygen is supplied only through portable bottles on the seat bottoms

Answer: (A)

In a depressurization event, the oxygen system is what keeps everyone on board breathing normally. When cabin pressure is lost, the oxygen masks for passengers automatically drop from the overhead panels so each person can put one on right away. The crew also has their own emergency oxygen masks at their stations, and those masks are designed to deploy automatically as needed. If automatic deployment isn’t functioning, or if the crew prefers to activate oxygen manually, they can engage it manually to ensure an immediate supply. This means oxygen is provided to both crew and passengers, not just to one group, and it isn’t limited to ground operations or to portable bottles.