Class B airspace typically extends from the surface up to:

Class B airspace surrounds the nation's busiest airports and is built as a series of stacked shelves — the inverted wedding cake — descending to the surface only in the innermost ring and stepping up as the rings move outward. The ceiling is uniform at 10,000 feet MSL, while the floor varies by ring, which is exactly why a remote pilot must read the chart rather than reason from the airport. A site several miles from the primary airport may sit beneath a shelf whose floor is 3,000 or 4,000 feet MSL, in which case the surface airspace is Class E or G and an unmanned operation at 200 feet may need no authorization at all. Under a ring that reaches the surface, authorization is required. LAANC serves many Class B locations and returns near-instant approval up to the published grid ceiling, but the pilot must first establish which ring the site is actually under.

Class B airspace has a uniform ceiling of 10,000 feet MSL, with floors that step upward in successive rings from the surface at the innermost one.

Class B airspace surrounds the busiest airports, extending from the surface or a shelf floor up to 10,000 feet MSL in stacked rings. Unmanned operations in Class B require authorization, commonly obtained through LAANC where available.

Ceiling Fixed at ten thousand, Floors Stepped outward. Only the middle ring reaches the ground.

Where the shelf floor is above the surface, the surface airspace is Class E or G and may require no authorization for a low operation.

• •Assuming Class B reaches the surface everywhere within its lateral limits
• •Confusing Class B dimensions with Class C or D
• •Reasoning from airport proximity rather than reading the shelf floor