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 student pilot endorsement requirements to operate within it.
Plain English
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.
Context Anchor
Pilots see Class B on aeronautical charts, during flight planning near major airports, and in radio communication with air traffic control.
Derivation
The FAA labels U.S. airspace alphabetically (A, B, C, D, E, G) roughly in order of how strictly it is controlled. B is the second-most restrictive class, used for the busiest airports where the highest level of separation and control is needed.
Why Pilots Care
Unauthorized entry risks a violation and compromises safety near high-volume traffic.
Intuition Check
Do not read Class B as a grade, quality level, or lesson category. Here it means a specific legally defined type of airspace around very busy airports.
Example Sentence 1
Before departing for Las Vegas, the pilot studied the Class B chart to plan a route that avoided entering the airspace without a clearance.
Example Sentence 2
VFR pilots must hold at least a private pilot certificate with specific training to operate in Class B airspace.