What is the primary function of the Fire 1 check during the over the rail checklist?

The primary function of the Fire 1 check during the over the rail checklist is to verify that the CWS (Central Warning System) panel and the AEDD (Advanced Engine Data Display) are not functioning in a manner that would indicate a fire condition. This part of the checklist is critical for ensuring that the aircraft's safety systems are operational and that there are no warning lights or alerts indicating a fire emergency.

If the CWS panel or other systems were signaling potential fire conditions, it would necessitate immediate attention and action from the crew, potentially affecting flight safety. This step ensures pilots are aware of the status of critical safety systems before advancing in their flight operations. A thorough understanding of the fire detection systems and their indicators is essential for maintaining safety during flight operations.