What action is crucial during a derailment situation?

In the context of a derailment situation, requesting for help immediately is critical because time is of the essence in emergencies. Quickly notifying emergency services ensures that assistance arrives as soon as possible, which can be vital for the safety and medical care of any injured individuals. Rapid communication can also facilitate coordination among first responders and can lead to a quicker overall resolution of the incident.

In contrast, waiting for the train operator’s instructions may delay necessary actions because the operator may not have immediate communication or information about the status of the situation. Keeping all passengers on the train can be a safeguard in certain scenarios, but only if it’s deemed safer than evacuation, which may not be the case in a derailment. Moving injured passengers to safety is important, but it typically comes after assistance has been requested and when it's safe to do so. Therefore, the immediate need to call for help and secure necessary resources takes precedence in managing the critical aftermath of a derailment.