In very simple terms, that means that both the pilot and aircraft will need to be instrument rated and be on an IFR flight plan. There is NO VFR flying allowed. You will need a clearance from ATC before you are permitted to enter Class A airspace.

Class A airspace is the most restrictive and controlled environment in the sky, typically extending from 18,000 feet Mean Sea Level (MSL) up to and including 60,000 feet (Flight Level 600). Access is strictly limited to pilots and aircraft operating under Instrument Flight Rules (IFR). This means that all pilots entering this space must hold an instrument rating and the aircraft must be equipped with a mode C or S transponder and two-way radio communication capabilities. Visual Flight Rules (VFR) flight—often used by recreational pilots—is completely prohibited in Class A. Before entering, a pilot must receive an explicit Air Traffic Control (ATC) clearance. The primary occupants are commercial airliners, corporate jets, and military aircraft. In 2026, the FAA and other international bodies maintain this "sterile" environment to ensure that all traffic is separated and monitored by ground-based radar or ADS-B technology, minimizing the risk of mid-air collisions at high altitudes where speeds are extreme and reaction times are short. If you are a private pilot without an IFR flight plan, you are legally required to remain below the "floor" of Class A.