Below what altitude is the speed limit strictly 250 KIAS?

The speed limit of 250 knots indicated airspeed (KIAS) below 10,000 feet is established by Federal Aviation Administration (FAA) regulations to help manage traffic in busy airspace and to reduce noise pollution near airports. This limit is a critical safety and operational measure that applies to all aircraft flying below this altitude, regardless of their size or type.

Maintaining this speed limit allows for better spacing and separation between aircraft, which is especially important in congested air traffic environments. Above 10,000 feet, the regulations allow for higher speeds to accommodate the different operational needs of aircraft as they climb to cruising altitude, where the airspace is typically less congested. Thus, the altitude of 10,000 feet is significant for establishing controlled airspeed limits to promote safety and streamline air traffic operations.