What is required when conducting a Class 1A 1000 mile air brake test?

When conducting a Class 1A 1000 mile air brake test, achieving a 20-pound brake pipe reduction is crucial. This reduction is a key requirement as it ensures that the air brake system is functioning correctly and effectively. The 20-pound reduction confirms that the brakes can respond appropriately to a signal and that the system has the necessary pressure to activate the brakes properly across the train's length.

This aspect of the air brake performance is vital for safety, as it helps to verify the effective functioning of both the locomotive and the train's brakes under operational conditions. Meeting the 20-pound reduction standard demonstrates that the train can reliably stop when needed and that the air brake components are in suitable working condition.

In the context of the other answer choices, while operational lights and adjustments to the brake system's pressure are also important for overall safety and functionality, they do not specifically pertain to the Class 1A test requirements related to brake force verification in the same direct way that the 20-pound reduction does. Conducting the test at night is not a necessity and does not influence the requirement for brake functionality in this specific context.