What altitude range defines Class A airspace?

Class A airspace is defined as the airspace from 18,000 feet mean sea level (MSL) up to 60,000 feet MSL. This airspace is typically utilized for high-altitude flights and is where air traffic control (ATC) provides services to ensure the safe and efficient movement of aircraft. All operations in Class A airspace must be conducted under instrument flight rules (IFR), meaning that pilots must have special training and instruments to fly in this controlled airspace.

Understanding Class A is crucial for operators of unmanned aircraft systems (UAS), as they need to be aware of airspace classifications to avoid violations and ensure safety in their operations. The altitude range of 0-10,000 feet and 1,200 to 18,000 feet mentioned in other options corresponds to Class G and Class E airspace, respectively, while the range of 0-4,000 feet would not adequately encompass Class A airspace at all.