What should be done first when loss of motor power occurs on the PA4 train?

In the event of a loss of motor power on the PA4 train, the most critical first step is to notify the Trainmaster. This action is essential because the Trainmaster is responsible for managing train operations and safety protocols. By informing them about the power loss, they can assess the situation, determine the necessary resources to assist, and coordinate any required responses.

Communication is vital in managing incidents effectively, ensuring that the appropriate safety measures are put into place, and allowing the affected train to receive necessary assistance or instructions. It's also important for operational coordination and maintaining overall safety on the rail network.

Other options, while related to troubleshooting or responding directly to the issue at hand, come after notifying the Trainmaster. Checking air compressor switches, releasing brakes to proceed, or adjusting the brake handle position are actions that may be necessary but are typically followed by communication with the central control or the Trainmaster to ensure that all safety protocols are being followed and that the situation is being managed appropriately.