What is the designated speed limit below 10,000 feet?

The designated speed limit below 10,000 feet is 250 knots indicated airspeed (KIAS). This regulation is primarily established to ensure safety in airspace that is more congested, since aircraft operating in this range often include both commercial airliners and smaller general aviation aircraft.

The limit of 250 KIAS serves to reduce the risk of mid-air collisions and to enhance the ability to handle traffic effectively, as aircraft generally operate at slower speeds in the terminal area and during approach and landing phases. This speed restriction helps provide a safer operating environment and allows for more effective air traffic control, which is particularly crucial when the airspace is busy.

Flying below this speed limit allows pilots better visual and operational control over their aircraft while managing interactions with other nearby aircraft. Adhering to the 250 KIAS limit also complies with Federal Aviation Administration (FAA) regulations, thereby ensuring standardized practices across the aviation industry.