In addition to warning bells or lights, what action may the cabin altitude warning system perform?

• A. Deploy automatic passenger oxygen masks
• B. Open the emergency exit
• C. Increase cabin pressure
• D. Drop cabin lights to dim

Answer: (A)

When the cabin altitude warning system detects unsafe cabin pressure, it not only sounds and lights the warning but can also automatically release the passenger oxygen masks. This immediate oxygen supply helps passengers breathe as the aircraft descends or stabilizes, buying time for the crew to manage the situation. The other actions aren’t functions of this warning system: opening an emergency exit isn’t automatic and would be dangerous to do at altitude; increasing cabin pressure isn’t something the system can enforce on its own during a decompression; and dimming cabin lights is unrelated to handling a loss of pressurization.