When using nonradar separation minima, when must the transfer of communication be made?

Answer: B — 5 minutes before reaching the boundary

The transfer of communication must be made 5 minutes before reaching the boundary when using nonradar separation minima. This guideline ensures that air traffic controllers have adequate time to communicate necessary information, coordinate the transfer of responsibility for an aircraft’s guidance and monitoring, and confirm that the receiving controller is prepared to take over. Making the transfer at this specific time is crucial in maintaining safe separation and ensuring that the aircraft does not enter airspace without the receiving controller being fully aware and ready. This practice contributes to minimizing the risk of communication delays which could lead to unsafe flight situations, thereby enhancing the overall safety of air traffic management.