In what airspace can pilots fly only under IFR rules?

In aviation, Class A airspace is exclusively designated for Instrument Flight Rules (IFR) operations. Pilots flying in Class A airspace must operate under IFR at all times, as this airspace is typically found at high altitudes starting from 18,000 feet up to 60,000 feet. The reasoning behind this regulation is to ensure safe separation between aircraft operating in high-density and potentially busy airspace, where visual flight is not feasible due to altitude and weather conditions.

The requirements for flying in Class A include the need for a flight plan filed under IFR and the necessity for pilots to have an instrument rating. This setup enhances safety by controlling the flow of aircraft, where air traffic controllers actively manage the traffic and provide services to maintain separation.

In contrast, the other classes of airspace allow for different types of flight rules. For example, Class G and Class E airspace permit operations under both VFR (Visual Flight Rules) and IFR, and Class D airspace can also accommodate both VFR and IFR operations, though requirements differ. Understanding the classifications of airspace is crucial for pilots to ensure compliance with the regulations that govern their flight operations.