What is it called when an employee has one supervisor that he answers to all the time?

The concept that describes an employee having one supervisor to whom they report at all times is known as unity of command. This principle is essential in organizational structures, particularly in emergency services like fire departments, as it promotes clarity in responsibilities and accountability. Unity of command ensures that each employee receives directives from a single source, reducing confusion, conflicting instructions, and potential miscommunication. By having one clear line of authority, it allows for streamlined decision-making and better coordination among team members during operations. This structure is vital in high-stakes environments where teamwork and clear leadership are crucial for effective response and safety.