When should the initial call up be made when operating at an airport with a control tower?

The initial call-up when operating at an airport with a control tower is typically made at a distance of 15 miles from the airport. This distance allows enough time for air traffic control to acknowledge your presence and provide any necessary instructions or clearance before you arrive. The 15-mile call-in distance ensures safe and efficient management of air traffic, allowing controllers to sequence arrivals and departures adequately. Making the call at this distance also helps pilots receive timely information about runway conditions, traffic, and other critical updates that may affect their approach and landing.

Other distances, such as 5, 10, or 20 miles, may not provide the optimal timing for communication, potentially leading to confusion or delays in air traffic management. Thus, the 15-mile distance strikes a balance between being adequately prepared and maintaining safety and efficiency in the airspace.