What must occur to return to normal operation after accepting a call-on?

To return to normal operation after accepting a call-on, getting clearance from the Trainmaster is essential. This step ensures that all safety protocols and operational guidelines are followed before proceeding. The Trainmaster has the authority to oversee train movements and ensure that the route is clear and safe for the train to continue.

The clearance from the Trainmaster acts as a confirmation that any potential hazards have been addressed and that it is safe for the train to move forward, thus maintaining safety standards and operational integrity. By waiting for this clearance, crew members demonstrate adherence to procedural requirements that are crucial in preventing accidents and ensuring the smooth operation of the rail system.

Other responses may not contribute effectively to the safe return to normal operations, as they either do not address the need for supervisory approval or may introduce unnecessary delays or complications.