On a sectional chart, airport information such as a CTAF frequency is shown in the airport data block. The CTAF is identified by:
Why →
The Common Traffic Advisory Frequency (CTAF) at non-towered airports is shown in the airport data block, typically marked with a solid magenta dot (or 'C' inside a filled circle, depending on chart series). The CTAF is used by pilots to announce position and intentions at uncontrolled airports.The trap →
Drone pilots do not broadcast on CTAF, but knowing how to find it matters for pre-flight planning; hearing a manned aircraft announce position can change the decision to launch nearby.SOURCE → FAA Aeronautical Chart User's Guide; AIM 4-1-9CHECKED APR 21ACS II.A.K5EASY