According to FAR Part 91.117, what is the maximum authorized airspeed for aircraft below 10,000 feet MSL?

Under FAR Part 91.117, the regulation specifies that the maximum authorized airspeed for aircraft operating below 10,000 feet mean sea level (MSL) is 250 knots indicated airspeed (KIAS). This rule is in place to maintain safe and efficient air traffic conditions, particularly in congested airspace where aircraft may be operating closer together. The 250 KIAS limit helps reduce the risk of wake turbulence and allows for better handling and predictability of flight operations in lower altitudes, where more maneuvering is often required.

This regulation is designed to facilitate the safe transit of aircraft in the airspace system, particularly in the vicinity of airports and in terminal airspace, where many aircraft are operating in a limited vertical and horizontal space. Other options listed, such as 200 KIAS, 300 KIAS, and 400 KIAS, do not apply to the restrictions set below 10,000 feet, as they exceed the maximum allowable speed for aircraft operating can lead to increased stress on both aircraft and air traffic control systems.