What is required to enter Class A airspace?

To enter Class A airspace, an IFR flight plan and clearance from Air Traffic Control (ATC) are required. Class A airspace generally extends from 18,000 feet up to and including flight level 600, and it is primarily utilized by aircraft operating under instrument flight rules (IFR). The requirement for an IFR flight plan ensures that the flight is conducted safely and efficiently among heavy air traffic in this typically busy airspace. Additionally, obtaining ATC clearance is essential because it allows air traffic controllers to manage the aircraft's movement, maintaining safe separation from other aircraft.

This system is designed to ensure effective communication and coordination in an airspace where pilots cannot rely solely on visual references due to altitude, weather conditions, or other factors.