Plain English Meaning

The protected airspace around the country's busiest airports. You cannot fly into it without first being told 'cleared into the Class B' by air traffic control.

Full Definition

Class B is a category of controlled airspace surrounding the busiest airports in the United States, generally extending from the surface up to 10,000 feet MSL and shaped like an upside-down wedding cake with progressively wider rings at higher altitudes. Entry requires a specific ATC clearance, and all aircraft inside must be in two-way radio contact with ATC and operating a transponder with altitude reporting. Pilots must hold at least a private pilot certificate or meet specific requirements to operate within it.