What is the initial action to take if a circuit breaker has popped?

When a circuit breaker has popped, the correct initial action is to immediately notify the captain. This step is crucial as it ensures that the flight crew is aware of any electrical issues in the aircraft, which can be critical for the safety and functioning of the flight. The captain, being responsible for the overall safety of the aircraft and its passengers, is trained to assess the situation, determine the appropriate response, and decide whether a reset is safe or if further action is needed.

Notifying the captain first gives them the opportunity to prioritize the issue, consult checklists, communicate with the ground or maintenance personnel if necessary, and make informed decisions based on their expertise and the specific situation on board. This prioritized communication is essential in aviation safety protocols.