Which principle requires each person to have only one direct supervisor?

The principle that requires each person to have only one direct supervisor is unity of command. This concept is fundamental in organizational structure, particularly in the context of emergency services such as firefighting. Unity of command ensures that an individual receives orders and is accountable to one designated supervisor, which helps to prevent confusion and conflicting directives that could arise if there were multiple supervisors.

By adhering to this principle, organizations can maintain clear lines of authority and responsibility, making it easier for personnel to understand their roles and for supervisors to manage operations effectively. This is particularly critical in high-stress situations like fire incidents, where quick and decisive actions are necessary.

Understanding unity of command is essential for maintaining order within a hierarchy, enhancing communication, and ensuring a cohesive team response, which is vital for the safety and efficacy of firefighting efforts.