Which altitude is the upper limit for Class A airspace?

Class A airspace is a designated area of controlled airspace that extends from 18,000 feet Mean Sea Level (MSL) up to 60,000 feet MSL, also referred to as Flight Level (FL) 180 to FL 600. The primary purpose of Class A airspace is to ensure that aircraft operating in this region, which includes high-altitude jet traffic, can do so safely and efficiently under Instrument Flight Rules (IFR).

The correct answer identifies FL600 as the upper limit of Class A airspace, signifying that operations within this airspace require pilots to adhere to specific regulations that help maintain organized aircraft operations and separation. This is crucial for safety, especially where high-speed jet traffic commonly operates.

Understanding the classification of airspace and the respective altitudes associated with each type is essential for pilots and aviation personnel as it dictates the operational rules, communication protocols, and navigation requirements they must follow.