When are oxygen masks deployed?

• A. When the cabin loses pressurization
• B. Only during takeoff
• C. Only during oxygen generator maintenance
• D. When the cabin loses pressurization or in certain emergency scenarios requiring supplemental oxygen

Answer: (D)

Oxygen masks are deployed whenever the cabin air is not safe to breathe and supplemental oxygen is needed. In flight, the most common trigger is a loss of cabin pressurization: when the aircraft can’t maintain a safe cabin pressure, masks automatically drop from panels above the seats so people can breathe as the plane descends to a breathable altitude. Masks can also be used in other emergencies that require supplemental oxygen, such as smoke, fumes, or certain medical situations, where having additional oxygen helps passengers and crew stay conscious and safe.

This isn’t limited to takeoff, and it isn’t a procedure reserved for maintenance scenarios. Those situations don’t reflect everyday operations; the automatic mask deployment during depressurization, plus its use in other oxygen-needed emergencies, is the standard safety design.