What criteria should be met before a controller can reduce separation distance in flight?

The requirement for a controller to reduce separation distance in flight is primarily based on established operational protocols, specifically outlined in Letters of Agreement (LOA). An LOA contains specific provisions and procedures that facilitate cooperation and coordination between various control facilities. It serves as a governing document that defines how separation can be altered under certain circumstances, ensuring safety and efficiency in managing air traffic.

Therefore, a controller is authorized to reduce separation only if it is clearly stated in the LOA, which regulates such actions in relation to airspace management. This authorization ensures that all actions taken align with predetermined safety standards and protocols that have been agreed upon between different air traffic facilities. Taking actions based on LOAs helps maintain standardization and safety in operations across various sectors of air traffic control.

The other potential options—such as attendance in a special training session, the discretion of the controller, or weather conditions—while potentially relevant in specific contexts, do not serve as universally applicable criteria for reducing separation distance.