If approach control service is not provided, the altimeter setting should be issued at what distance from the destination airport?

The correct answer is based on established guidelines for issuing altimeter settings when approach control service is not provided. The standard practice is to provide the altimeter setting to pilots at 50 nautical miles from the destination airport. This distance allows sufficient time for pilots to adjust their altimeter settings and offers a smooth transition as they approach the airspace for landing.

Issuing the altimeter setting at this distance helps ensure that pilots are operating with accurate altitude data as they descend, which is crucial for maintaining safe separation from terrain and ensuring correct altitudes on final approach. The 50-mile mark strikes a balance between giving pilots enough time to make necessary adjustments without issuing the information too early or too late, which could lead to miscalculations during descent.