Which airspace requires ATC clearance before entry?

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

Answer: (B)

Class B airspace is the one that requires explicit ATC clearance before you may enter. This airspace surrounds busy airports and is tightly controlled to manage high traffic, so pilots must be granted a specific clearance by ATC prior to entering and must remain under ATC instructions once inside. Two-way radio communication with ATC is also required to ensure you’re being issued those clearances and sequencing instructions.

In contrast, Class A requires an IFR clearance to operate there (and VFR flight can’t enter), while Class C and D require establishing two-way radio communications with ATC before entry and following ATC instructions, but not a separate entry clearance in the same sense as Class B.