What should be done to ensure the POB is functioning before placing a mask on a passenger?

To ensure that the Portable Oxygen Bottle (POB) is functioning properly before applying a mask to a passenger, it is essential to hold the mask to the face to feel for the flow of oxygen. This action directly assesses whether the oxygen is being dispensed as intended. If oxygen flow is present, it confirms that the system is operational and ready to support the passenger's needs.

In a practical setting, merely checking for a green light on the POB may not provide a complete assurance of functionality, as indicators can sometimes be misleading or malfunction. Turning the bottle upside down is not a standard procedure for testing its function and might not yield reliable results. Inspecting the bottle for leaks is important for maintenance and safety but does not confirm the immediate functionality of oxygen delivery, which is the critical concern when managing a passenger in need of oxygen. Thus, feeling for the flow through the mask offers immediate confirmation of the system's effectiveness and readiness for use.