What is the first step to conduct an Air Flow Method (AFM) test?

The first step to conduct an Air Flow Method (AFM) test is to charge the brake system to within 15 psi. This initial step is crucial because it ensures that the brake system is at an appropriate pressure level to accurately assess the performance of the air brakes during the test. Charging the system adequately allows for a reliable establishment of baseline air pressure, which is necessary for subsequent steps in the AFM testing procedure.

By achieving the correct pressure, it creates the necessary conditions to accurately measure how air flows through the system and to determine whether the air brakes will respond appropriately in service conditions. This standard procedure is essential to ensure safety and efficiency in the overall operation of the train's braking system.