What should be done if a defect or unsafe condition is found and communication with the inspected train is not possible?

In the scenario where a defect or unsafe condition is identified and communication with the inspected train cannot be established, the appropriate action is to immediately notify the train dispatcher. This step is crucial because the dispatcher plays a key role in managing train movements and ensuring safety across the network. By alerting the dispatcher to the issue, they can take necessary measures to address the situation, which may include halting the train's progress, sending maintenance personnel to assess the defect, or rerouting the train if it poses a risk to other operations.

The urgency of this action stems from the need to mitigate potential hazards and prevent accidents. Ensuring that the defect is documented and escalated to the right authorities allows for a coordinated response, which is essential in maintaining safety standards.

Continuing with the inspection could overlook serious safety concerns, while cutting the defective car from the train might be premature without proper authorization or communication, potentially leading to operational disruptions. Marking the car for later inspection does not address the immediate risk and delays necessary actions that could help prevent further safety incidents. Thus, notifying the train dispatcher represents the best and most responsible course of action in this situation.