How is passenger oxygen typically delivered during decompression?

• A. Masks with chemical oxygen generators
• B. Direct oxygen via seat-based hoses
• C. Nasal cannulas connected to the oxygen system
• D. Oxygen through the cockpit pressurization system

Answer: (B)

When cabin altitude rises, passengers need oxygen immediately, and the system is designed to deliver it quickly and reliably to everyone. Masks that hang from overhead panels have each one connected to a chemical oxygen generator built into the mask assembly. When you pull the mask toward you, the chemical generator starts producing oxygen on demand and delivers it through the mask to the wearer. This setup works independently for each passenger, so no one has to rely on any other part of the aircraft or on someone else activating a system.

Direct oxygen via seat-based hoses isn’t a standard in commercial airliners for decompression events; it would require a fixed, seat-by-seat supply and activation, which adds complexity and delay and isn’t how oxygen is reliably provided to all passengers. Nasal cannulas don’t provide sufficient oxygen at cabin altitudes and don’t deliver oxygen quickly enough for sudden decompression. Oxygen delivered through the cockpit pressurization system wouldn’t reach passengers in a controlled, timely way during a rapid drop in cabin pressure. The mask-and-generator system is specifically designed for fast, individual delivery to every passenger.