When is it appropriate to issue an aircraft conflict/Mode C alert?

Issuing an aircraft conflict or Mode C alert is appropriate when there is a belief that there is unsafe proximity between aircraft, regardless of the specific distance. This allows air traffic controllers to proactively address potential hazards and maintain safe separation between aircraft.

This approach emphasizes the need for situational awareness and the understanding that safety is paramount in air traffic management. While some situations might arise where specific distances or conditions trigger alerts, the broader guideline is based on the overall assessment of the situation.

Maintaining safe airspace involves constantly evaluating aircraft movements and being prepared to intervene if it seems that aircraft are on a collision course or too close to one another. Hence, this option captures the essence of safety-oriented decision-making in air traffic control.

The other options focus on specific conditions that do not encompass the broader safety assessment required to justify issuing an alert, making them less suitable for ensuring flight safety.