What are the altitude limits for Class A airspace?

Class A airspace begins at Flight Level 180 (FL 180) and extends up to Flight Level 600 (FL 600). This airspace is primarily used for high-altitude en route traffic and is designed to facilitate efficient and safe flight operations for aircraft traveling at higher altitudes.

The altitude begins at FL 180 specifically because this level is above the majority of air traffic and weather-related concerns that affect lower altitudes, such as turbulence and icing conditions. By regulating aircraft in this airspace and requiring them to operate under Instrument Flight Rules (IFR), air traffic control can maintain a higher density of air traffic, thereby enhancing safety and operational efficiency.

This option accurately reflects standard regulations for Class A airspace and demonstrates the structured nature of higher altitude operations in aviation. Other options do not encompass the correct range for Class A airspace, as they either start below FL 180 or extend beyond the upper limit of FL 600.