What kind of environment is referred to as a "non-radar environment"?

A "non-radar environment" refers specifically to an area lacking radar services for air traffic control. In such environments, air traffic controllers rely on more traditional methods of communication and navigation, such as pilot reports, visual observations, and position reports over radio. This might occur in less densely populated regions or where radar coverage is not available, necessitating the use of procedural separation between aircraft instead of the precise tracking that radar provides.

While other options mention scenarios related to traffic density or specific approaches, they do not accurately define what constitutes a non-radar environment. The absence of radar service is the defining characteristic, making it crucial for pilots and air traffic controllers to adapt to less immediate and less precise means of aircraft separation and tracking.