What type of O2 masks are installed for passengers in the cabin?

• A. Diluter-demand masks
• B. Continuous-flow masks
• C. Pressure-demand masks
• D. Oxygen-preserving masks

Answer: (B)

Oxygen delivery to passengers in the cabin is designed for immediate, dependable supply when masks deploy. Continuous-flow masks provide a steady flow of oxygen to the mask regardless of how the passenger breathes, ensuring a predictable and sufficient concentration of oxygen right away as cabin altitude rises. This simplicity and reliability are crucial in an in-flight emergency, where you want to avoid delays or variability in oxygen delivery that could occur if the mask only supplied oxygen on inhalation.

In contrast, a diluter-demand arrangement would only deliver oxygen during inhalation and blends it with cabin air, which can reduce and delay the effective oxygen delivered if breathing is shallow or erratic. A pressure-demand system is more complex and typically used in specialized environments and not the standard cabin setup. Oxygen-preserving masks are intended to conserve oxygen in small aircraft or specific configurations, not the general passenger cabin. So the cabin masks are designed as continuous-flow devices to ensure every passenger gets reliable oxygen immediately when needed.