What action must be taken if a brake application light stays lit in a charged train?

When a brake application light remains lit while the train is charged, the correct course of action is to inspect for any applied air brakes. This light indicates that the braking system is engaged, which could lead to a potential safety hazard if not addressed. Inspecting the brakes allows for ensuring that they are functioning correctly and are not inadvertently applied, which would affect the train's movement and could cause inefficiency or risk during operations.

In a charged train situation, failing to inspect for an applied brake could mean the train is not ready for a safe departure, as the brakes could create unnecessary resistance or cause operational issues. Attention to this light and subsequent inspection are critical for the safe operation of the train and the safety of its passengers and crew.