When should the parking brake be engaged?

The appropriate time to engage the parking brake is whenever the bus is parked. This ensures that the vehicle remains stationary and does not move unintentionally, particularly on an incline. Engaging the parking brake is a crucial safety measure that prevents accidents and protects both the bus and its passengers. It is a standard operating procedure in bus maintenance and operation to ensure the safety and security of the vehicle when it is not in motion.

While the other choices suggest engaging the brake during specific situations, only the practice of engaging it whenever the bus is parked comprehensively covers all necessary circumstances to ensure safety. This proactive approach addresses the risk of accidental movement regardless of the specific conditions faced by the bus when it comes to rest.