What is the speed limit below 10,000 ft AMSL in ICAO airspace classifications C, D, E, F, and G?

In ICAO airspace classifications C, D, E, F, and G, the speed limit below 10,000 feet above mean sea level (AMSL) is set at 250 knots indicated airspeed (IAS). This regulation is established to ensure the safety and efficiency of air traffic operations, especially in controlled airspace where there are frequent interactions between various types of aircraft, including commercial airliners and general aviation.

Maintaining this speed limit helps in managing the flow of air traffic and reducing the likelihood of wake turbulence encounters, thus enhancing safety. This is especially important in busy airspace, where multiple aircraft may be operating concurrently at lower altitudes. The speed restriction helps avoid congestion and conflict at critical altitudes where most aircraft are climbing or descending.

Other speed limits, such as 200 knots (typically applicable in specific situations near airports), 300 knots, or 350 knots, may be relevant in different contexts or specific areas. However, below 10,000 ft in the mentioned airspace classifications, the established standard is 250 knots IAS to ensure uniformity in air traffic management across different countries and airspace types as governed by ICAO regulations.