What are the altitude limits for Class A airspace?

Class A airspace is defined as the airspace from Flight Level 180 (FL 180) to Flight Level 600 (FL 600). This airspace is typically located at higher altitudes and is used primarily by jet aircraft flying in the enroute phase of their flight. The primary characteristic of Class A airspace is that it is managed under Instrument Flight Rules (IFR) and all aircraft operating in this class must be equipped and qualified for IFR operations.

The lower limit, FL 180, is the boundary above which the airspace becomes Class A, meaning that any flights operating below this altitude are subject to different airspace classifications with varying rules and regulations. Since Class A airspace begins at this altitude and goes all the way up to FL 600, it creates a volume of airspace exclusively for high-altitude, high-speed aircraft operations.

Options suggesting different altitude ranges do not align with the criteria established for Class A airspace and reflect a misunderstanding of its defined limits.