Which alert is indicated by the APU fire light on the pilot's enunciator panel?

The APU fire light on the pilot's enunciator panel indicates a potential fire condition in the Auxiliary Power Unit. This alert is represented by a steady light, which signifies that there is a significant and immediate concern regarding fire in the APU compartment.

The steady light informs the pilot that an abnormal situation requires immediate attention, as it is designed to convey urgency about the presence of a fire hazard. In contrast, other alert types such as a continuous sound or a flashing light are typically used for different warnings or indications within aircraft systems, reflecting different levels or types of urgency. The absence of an alert would imply that no issues are present, which does not align with the purpose of the APU fire light. Therefore, the correct identification of the APU fire light's function is crucial for pilot safety and operational integrity.