Which of the following describes Class A airspace?

Class A airspace is defined as the airspace from 18,000 feet MSL (Mean Sea Level) up to 60,000 feet MSL. It is the region where all aircraft operations are conducted under Instrument Flight Rules (IFR), and pilots must operate with an IFR flight plan. This high-altitude airspace is typically located over busy air traffic routes and is managed by air traffic control to maintain safe separation between aircraft.

This regulation ensures that pilots in Class A airspace are appropriately trained and that their aircraft are equipped to meet higher-level flying standards. Knowing the altitude limits for Class A airspace is crucial for maintaining compliance with these regulations and for effectively planning flight routes that may enter or exit this airspace.

Other choices describe characteristics of different classes of airspace or fail to accurately define Class A, which centers around its specific altitude range and operational requirements.