What should be the immediate action if the circuit breaker pops?

When a circuit breaker pops, the immediate action should be to notify the flight deck. This is crucial because the flight deck crew needs to be aware of any issues that may affect the aircraft's electrical systems, which could impact the safety of the flight. The flight crew has the necessary training and resources to assess the situation and determine the appropriate response. They can also decide if any additional measures need to be taken, such as monitoring specific systems or preparing for potential abnormalities that may arise from the circuit breaker tripping.

In this context, notifying the passengers or attempting to reset the circuit breaker doesn’t address the immediate need to inform those who are responsible for managing the aircraft’s operation. Turning off all power might lead to unnecessary complications, and without proper procedures in place, it could create further risks. The best practice is to keep the flight deck informed so they can take the necessary actions based on the aircraft's systems status.