What is the first step required to perform a locomotive air brake test?

The first step in performing a locomotive air brake test is to observe the brakes apply on each locomotive. This step is critical because it allows the crew to verify that the air brakes are functioning properly on the locomotive. Observing the application of brakes ensures that the system is responding correctly to inputs and that there are no leaks or mechanical failures preventing the brakes from engaging.

Successfully checking the application provides confidence in the overall air brake system's reliability. It's an essential safety check before proceeding with further operations or tests. This step sets the foundation for subsequent actions in the brake test process, as it confirms that the air brake system is properly sealed and operational. After confirming the application of the brakes, other steps like making reductions or releasing brakes can be followed, but the initial observation is paramount to ensure safety and functionality.