When must a locomotive consist air brake test be completed?

Answer: B — When changing operating ends of a consist

The necessity to complete a locomotive consist air brake test when changing operating ends of a consist is crucial for ensuring the safety and functionality of the braking system. This procedure allows for the verification that all components of the air brake system are operating correctly after the change in operational direction, which can affect the dynamics of air pressure and the overall braking capabilities of the train. Conducting the test at this point helps to identify any potential issues that might have arisen due to the reversal of ends, ensuring that the locomotive and the train are safe to operate in the new direction. It reinforces the reliability of the brake system, which is essential in maintaining control of the train throughout its journey.