What is the purpose of the blue indicator on the PBE?

The blue indicator on the Portable Breathing Equipment (PBE) serves as a readiness signal, indicating that the device is prepared for use. When this light is illuminated, it confirms that the PBE has been correctly assembled and is ready to provide an adequate air supply for the user in an emergency situation. This is crucial for flight attendants and crew members who must quickly assess and utilize safety equipment during in-flight emergencies.

The other options reflect different functions that are not represented by the blue light. For instance, a low battery indicator would suggest a need for immediate attention but does not pertain to the blue readiness signal. Similarly, a confirmation of air supply and a malfunction signal would typically have different indicators, ensuring that the crew can easily distinguish between various operational statuses of safety equipment.