What is the required communication distance prior to approaching to land in Class D airspace?

In Class D airspace, pilots are required to establish two-way radio communication with the air traffic control (ATC) facility prior to entering the airspace. The required communication distance is four nautical miles (NM) from the airport up to and including 2,500 feet above ground level (AGL). This measure is in place to ensure that pilots are aware of air traffic in the vicinity and can receive instructions or advisories from ATC, thereby enhancing safety during approach and landing operations.

This distance allows pilots sufficient time to communicate with ATC, and the altitude limits specify the vertical space where this communication must be acknowledged. Understanding this requirement is crucial for pilots flying within Class D airspace, as failing to establish communication could lead to safety violations or increased congestion in the airspace.