What additional line of the CAS 9-line is a mandatory readback when working with NATO forces?

The mandatory readback when coordinating Close Air Support (CAS) with NATO forces is Line 8, which provides the location of the friendlies in relation to the target area. This line is critical because it helps ensure that all parties involved have a clear understanding of where friendly forces are positioned, thus minimizing the risk of fratricide during an airstrike.

The importance of Line 8 lies in its role in the operational safety of ground troops. Unlike other lines that provide essential information such as target location or description, Line 8 specifically communicates the placement of friendly forces to aircraft and ground controllers, reinforcing situational awareness and collaboration among NATO allies during operations.

This emphasis on Line 8 reflects NATO's commitment to safety and precision in joint operations, necessitating that all units clearly communicate this information for effective coordination and to maintain the integrity of friendly forces in the field.