What action is taken to ensure a safe departure once the engine is running?

Removing the wheel chocks is a critical action to ensure a safe departure once the engine is running because these chocks are used to prevent the aircraft from moving unintentionally while it is stationary. When the engines are started, the aircraft can be subject to thrust that may cause it to roll if the chocks are not removed. By ensuring that the wheel chocks are taken away, you eliminate the risk of an inadvertent movement of the aircraft while still on the ground, thereby contributing to safer operations during departure.

In contrast, preparing for passenger boarding, confirming the flight plan, and notifying ground control, while important procedures in their own right, do not directly relate to preventing the aircraft from moving unexpectedly once the engines are running. These tasks typically take place before engine start or in conjunction with other pre-departure protocols, but the removal of the wheel chocks is specifically aimed at ensuring the aircraft remains secure once the engines are active.