Within which distance from the primary airport is the maximum airspeed regulation applicable in Class D airspace?

In Class D airspace, the maximum airspeed regulation is specifically applicable within a defined range of the primary airport. This range is set at 4 nautical miles (NM) from the airport's location. The regulation mandates that aircraft operating in this vicinity must not exceed a maximum airspeed of 200 knots indicated airspeed (KIAS) when below 2,500 feet above the ground.

This 4 NM distance is significant because it allows air traffic control to maintain safer and more orderly traffic flows around the airport, accommodating both arriving and departing aircraft. The regulation is designed to minimize the risk of collisions and to allow for easier management of air traffic in a busy airspace environment, particularly near the airport where there could be numerous aircraft operating at lower altitudes.

Understanding these specifics about Class D airspace is crucial for safe navigation and compliance with air traffic regulations, especially for pilots operating in congested urban areas or near busy airports.