What altitude should turbojet arrivals operating at or above 11,000' cross the lateral boundary at?

The correct altitude for turbojet arrivals operating at or above 11,000 feet to cross the lateral boundary is 11,000 feet because it is essential that arrivals maintain a safe and efficient altitude while transitioning into controlled airspace. The requirement to cross at this level ensures that there is adequate vertical separation from any traffic below that is operating at lower altitudes. By specifying that turbojets at or above 11,000 feet should cross at precisely that altitude, air traffic control can maintain organized traffic flows and optimize the use of airspace. This standard helps prevent potential altitude conflicts with other aircraft.

Other altitude choices do not fit the operational requirement for turbojets arriving from higher altitudes. For example, crossing at 12,000 feet or at 14,000 feet would not accommodate the operational needs of arrivals already cruising at 11,000 feet, while crossing lower at 10,000 feet could lead to conflicts with departing or ascending aircraft still in the airspace. Hence, the established protocol emphasizes that turbojet arrivals should cross the lateral boundary at their current altitude when at or above 11,000 feet.