What course of action is required after several failure attempts to communicate with the flight deck?

The recommended course of action after several failed attempts to communicate with the flight deck is to push the door. This action pertains to a critical safety protocol in aviation, where flight attendants must ensure the safety and security of the cabin and the passengers. If communication cannot be established with the flight deck, it may indicate a serious situation. Pushing the door allows the flight attendant to access the flight deck if necessary, as the priority in such cases is to ensure contact with the pilots and assess the situation promptly.

In this context, other options may not directly address the immediate need for communication with the flight deck. Contacting airport control is typically done after establishing communication with the flight deck, while notifying security may be out of context unless there is a perceived threat. Waiting for further instructions does not resolve the lack of communication and can potentially delay response actions that might be crucial for the safety of everyone on board.