What is the altitude threshold for high altitude enroute charts?

The altitude threshold for high altitude enroute charts is 24,000 feet. High altitude enroute charts are designed for aircraft operating at altitudes above this threshold, effectively catering to the needs of high-altitude air traffic where navigation and route planning differ due to the specific characteristics of airspace, including separation requirements and air traffic management.

The charts incorporate information and navigation aids suitable for operations that occur typically at altitudes where flight levels are expressed in hundreds of feet, specifically starting from FL 240 (which is 24,000 feet) and above. This ensures that pilots have relevant data for safe navigation in the upper airspace, where different regulations and navigational considerations apply compared to lower altitudes. Understanding these charts is crucial for pilots who operate in controlled airspace at high altitudes, optimizing their navigation and situational awareness.