Which indicator must be extinguished when the crew entrance door is properly closed and locked?

• A. Door Open Lights
• B. Master Caution
• C. No Smoking Sign
• D. Cabin Pressure Indicator

Answer: (A)

The main idea here is that indicators tied to the crew entrance door reflect whether the door is fully closed and latched. When the door is properly closed and locked, the door open lights must be extinguished. These lights are designed to illuminate if the door isn’t fully seated or hasn’t engaged the lock, signaling an unsafe condition that requires attention. Extinguishing them confirms the door status is secure, allowing normal operations.

The other indicators aren’t directly related to door status: a Master Caution light signals a general fault or abnormal condition in the aircraft systems, not specifically the door; the No Smoking Sign is a passenger safety reminder and not a door-status indicator; the Cabin Pressure Indicator shows pressurization status, which is independent of whether the crew entrance door is closed.