Definition
A radio frequency designated for pilots to broadcast their position and intentions when operating at airports without an active control tower, so that nearby aircraft can coordinate with each other directly. The frequency may be a UNICOM, MULTICOM, FSS, or tower frequency (when the tower is closed), and is published on aeronautical charts and in the Chart Supplement.
Plain English
It's the shared radio channel pilots use to talk to each other near small or untowered airports. Instead of a controller telling everyone what to do, pilots announce what they're doing so other pilots in the area know who's where.
Context Anchor
Seen on airport information pages, charts, and in preflight planning for airports that do not have an operating control tower at that time.
Derivation
Common because everyone in the area shares the same frequency. Traffic Advisory because pilots are advising each other about traffic — there's no controller issuing instructions, just pilots making position calls.
Why Pilots Care
It enables pilots to maintain separation and situational awareness without ATC services, directly reducing mid-air collision risk in the airport environment.
Intuition Check
Common does not mean casual or optional here. It means the one shared frequency pilots are expected to use for traffic calls at that airport.
Example Sentence 1
Ten miles out, the pilot tuned the CTAF and announced her position and intentions to land.
Example Sentence 2
All aircraft in the pattern were monitoring the Common Traffic Advisory Frequency to coordinate their approaches.