Which document supplements interfacility operations?

The correct answer, which is the Letter of Agreement (LOA), is critical in enhancing clarity and efficiency in interfacility operations. An LOA is a formal agreement between two air traffic facilities that outlines the specific procedures and responsibilities for the coordination of aircraft operations between them. This document details the operational protocols, communication procedures, and any specific traffic management measures that need to be adhered to, ensuring that there is a mutual understanding and a coordinated approach to managing airspace and ensuring safety.

While other documents play important roles in air traffic operations, they focus on different aspects. For instance, the Air Traffic Coordination Agreement typically addresses the protocols at a broader level, rather than specifically delineating the responsibilities of separate facilities. Standard Operating Procedures (SOP) are internal guidelines for an individual facility's operations, not meant for interfacility collaboration. The Sector Management Plan outlines how airspace should be managed within a specific sector but does not specifically cover the operational linkages between multiple facilities. Therefore, the LOA stands out as the essential document that supplements and specifies the collaborative efforts between different air traffic control facilities during interfacility operations.