What is the initial action to take if you notice the yellow light on the HUD?

When the yellow light on the Heads-Up Display (HUD) of a Self-Contained Breathing Apparatus (SCBA) is triggered, it indicates that the air supply is approaching a lower level. The initial action should be to check the air supply to accurately assess how much air remains in the tank. This step is crucial for ensuring the safety of the user and others, as it allows for informed decision-making regarding whether to continue with the current operations, refill the tank, or transition to a different course of action. Understanding the air supply status helps in determining the necessary next steps and planning for safe egress from the area if required.