Airspace Classification, Operating Requirements, and Flight Restrictions
The airspace ladder
Class A begins at 18,000 ft MSL and is off-limits to small UAS. Class B, C, D, and Class E surface areas all require ATC authorization under §107.41 before you launch; Class E above 700 or 1,200 ft AGL and Class G need none. On a sectional chart, Class B is a solid blue line, Class C a solid magenta line, Class D a dashed blue line, and Class E surface area a dashed magenta line - solid for surface, dashed for surface area, magenta for Charlie and Echo. LAANC gives near-real-time authorizations in grid cells with ceiling values of 0, 50, 100, 150, or 400 ft; where LAANC is unavailable, use the FAA DroneZone airspace authorization process.
Other restrictions
TFRs, prohibited areas (P-), restricted areas (R-) when active, special flight rules areas such as the Washington DC SFRA, and MOAs sit outside the ATC-authorization system. A LAANC approval never overrides a TFR. Check NOTAMs and the chart before every flight. Near an airport in Class G, no authorization is needed, but §107.43 still forbids interfering with airport traffic.
Traps
The classic miss is a dashed magenta circle around a satellite airport - that is Class E surface area, so authorization IS required. A LAANC grid ceiling of 0 means no automated flight there. Class G is not a free pass next to a runway.
Rule of thumb
Ask two questions: does the chart show solid or dashed blue/magenta at my operating altitude (authorization needed), and is anything else - TFR, SFRA, P-area, R-area - layered on top?