Sectional chart reference
Class B
Solid blue lines (layered 'upside-down wedding cake').
What you are looking at
A solid, crisp BLUE line is a class boundary: solid blue = Class B, the busiest airspace, wrapping the biggest airports as an upside-down wedding cake.
A solid line is a real class boundary that reaches the surface. Someone is in charge all the way down. Memory hook: 'B is for Blue,' which anchors the whole grid (so the other solid line must be C).
The rule itself
No person may operate a small unmanned aircraft in Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from Air Traffic Control (ATC).
Quoted in full from 14 CFR § 107.41. Authorization normally comes through LAANC.
Reading the numbers
Each ring shows a fraction = that one layer's top over its own floor, both MSL, e.g. 110/40 = top 11,000 / floor 4,000 MSL. It is one cake layer seen from above, NOT two shelves.
Where people get this wrong
Don't confuse the solid blue LINE (Class B) with a faded blue BAND (a Class E floor at 1,200 ft). Line = class, fuzz = floor.
How it is tested
You're under a Class B shelf marked 100/40. What is the floor of that layer?
- 4,000 ft MSL
- 4,000 ft AGL
- 10,000 ft MSL
Show the answer
4,000 ft MSL
The fraction is that layer's top/floor, both MSL: top 10,000 / floor 4,000 MSL.
Find one near you
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