In Class D airspace, the maximum airspeed restriction of 200 knots indicated airspeed (KIAS) applies to aircraft below 2,500 feet above ground level (AGL). This regulation is enforced to maintain safety and prevent potential conflicts with surrounding aircraft, particularly as they operate in and out of airports located in such airspace.
When flying in Class D airspace, pilots must adhere to this limit, which helps to keep speeds manageable while pilots are conducting crucial tasks, such as approach and landing maneuvers. Therefore, the correct altitude where this airspeed limitation comes into effect is actually at 2,500 feet AGL. It is important for pilots to be aware of these restrictions as they plan their flights, in order to ensure compliance with air traffic control regulations and maintain operational safety in busy airspace.