What is the vertical extent of Class A airspace in the contiguous U.S.?

Class A airspace has specific vertical limits that are crucial for understanding air traffic control and navigation at higher altitudes. The vertical extent of Class A airspace in the contiguous United States is defined from 18,000 feet mean sea level (MSL) up to flight level (FL) 600, which is approximately 60,000 feet MSL. This designation allows for controlled airspace where only IFR (Instrument Flight Rules) operations take place, emphasizing the importance of maintaining a high level of pilot understanding concerning altitude.

The upper limit of Class A at FL 600 allows for operations of high-altitude traffic, including commercial airliners. Pilots must have the appropriate clearances and equipment to operate in this airspace due to its complexity and the high density of operations.