Class A airspace in the United States has which vertical limits and IFR flight plan requirement?

Class A airspace in the United States has which vertical limits and IFR flight plan requirement?

• A. From surface to 18,000 ft MSL, VFR allowed without clearance
• B. From 18,000 ft MSL up to FL600, IFR flight plan required
• C. From 5,000 ft MSL to FL300, VFR requirement
• D. From 10,000 ft MSL to FL200, IFR flight plan optional

Answer: (B)

Class A airspace begins at 18,000 ft MSL and extends up to FL600. In this airspace, all operations must be conducted under IFR and you must file an IFR flight plan and receive ATC clearance to enter. VFR operations are not permitted there. So the correct description is the vertical span from 18,000 ft MSL to FL600 with an IFR flight plan required. The other options mix up the floor or ceiling and imply VFR access or missing the clearance requirement, which aren’t true for Class A.

Class A airspace begins at 18,000 ft MSL and extends up to FL600. In this airspace, all operations must be conducted under IFR and you must file an IFR flight plan and receive ATC clearance to enter. VFR operations are not permitted there. So the correct description is the vertical span from 18,000 ft MSL to FL600 with an IFR flight plan required. The other options mix up the floor or ceiling and imply VFR access or missing the clearance requirement, which aren’t true for Class A.