Which airspace extends from the surface to 10,000 feet MSL surrounding the nation's busiest airports in terms of IFR operations or passenger numbers and requires ATC clearance to operate?

• A. Class A
• B. Class B
• C. Class C
• D. Class D

Answer: (B)

The situation describes the airspace around the nation’s busiest airports, designed to manage very high traffic volumes. This airspace extends from the surface up to 10,000 feet MSL and requires ATC clearance to enter. That clearance rule is the key feature: you must obtain explicit permission from ATC and establish two-way radio communication before operating there. A Mode C transponder is typically required within this airspace as well, reflecting the need for precise traffic separation in a busy environment. This is what makes it distinct from the other classes: it’s the only one that starts at the surface and goes up to 10,000 feet around the busiest hubs, with strict entry requirements and vertical structure to handle dense IFR and passenger operations.