ATIS vs CTAF explained: learn what each frequency does, when to listen or transmit, and how to use both correctly in aviation and flight simulators.
ATIS is a one-way broadcast of recorded airport, weather and operational information, identified by a letter code. CTAF is a shared radio frequency on which pilots announce positions and intentions at a non-towered airport, or when a tower is closed. In flight simulators, listen to ATIS; use CTAF to make traffic calls.
In Aviation & Real-World Flying, the practical distinction is that ATIS informs you, while CTAF helps pilots coordinate with one another. Our explanation of the ATIS frequency, content and information-code procedure covers that broadcast in greater depth.
ATIS vs CTAF at a glance
| Feature | ATIS | CTAF |
|---|---|---|
| Full name | Automatic Terminal Information Service | Common Traffic Advisory Frequency |
| Main purpose | Provides airport, weather and operational information | Lets pilots report positions and intentions |
| Communication | One-way broadcast to pilots | Shared pilot-to-pilot voice channel |
| Typical use | Selected towered airports | Non-towered airports and some towered airports after closure |
| What you hear | Wind, visibility, cloud, altimeter setting, runway and approach information, plus selected notices | Taxi, departure, arrival and traffic-pattern position reports |
| Identifier | A phonetic letter such as Alpha or Bravo | No information letter |
| Response expected | None; tell ATC which information code you received | Other pilots may respond when coordination is useful |
Voice ATIS normally repeats continuously and receives a new letter when its contents are revised. Digital ATIS provides equivalent information through compatible systems. A CTAF has no repeating message because it is a channel, not a broadcast station.
Can an airport use both ATIS and CTAF?
An airport may have ATIS during tower operations and a published CTAF for periods when the tower is closed, but they serve different phases and must not be treated as interchangeable.
- Tower operating: Listen to ATIS, then contact clearance delivery, ground or tower as appropriate. Use the ATIS code in the initial call, such as
with Information Bravo. Follow ATC instructions and readback requirements rather than making ordinary CTAF position calls. - Non-towered airport: Obtain weather from the published automated service if one exists, then monitor and transmit on CTAF. Many such airports have AWOS or ASOS rather than ATIS; these airport weather and information services have different functions.
- Tower closed: Check the published airport data. The tower frequency often becomes the CTAF, but this is not universal. ATIS may also stop or be replaced by an automated weather broadcast.
CTAF is chiefly FAA and North American terminology. Other countries may publish an aerodrome traffic frequency, mandatory frequency or a locally named service with different reporting rules. The charted frequency and local procedures always take priority.
How do you use ATIS and CTAF in a flight simulator?
The correct simulator workflow is to gather information first, select the frequency appropriate to the airport's operating status, and then communicate.
- Check the airport frequencies. Use the simulator's airport information, charts or navigation data. Do not assume that every non-towered airport uses the same common frequency.
- Listen to ATIS or automated weather. Copy the active runway, wind, visibility, cloud, altimeter setting and ATIS letter. ATIS is not a substitute for all published notices or a complete pre-flight briefing.
- Select the correct communication channel. Contact ATC when the simulated tower is active. Use CTAF when the field is non-towered or the tower is closed and that frequency is published.
- Make concise position reports. State the airport name, aircraft identification, position and intention. Repeat the airport name at the end where local phraseology calls for it.
- Keep looking for traffic. A CTAF transmission does not create a clearance, establish separation or guarantee that another aircraft heard the call.
Simulator implementations vary. Some built-in ATC systems provide ATIS but offer only menu-driven CTAF calls; others play no response because there is no simulated station listening. During online human-controlled flying, transmit only when the network's procedures and airport status require it.
What should you say on CTAF?
A useful CTAF call identifies where you are and what you intend to do without occupying the frequency unnecessarily. For example: Springfield traffic, Cessna One Two Three Alpha Bravo, entering left downwind runway two-seven, Springfield traffic.
Typical calls cover the inbound position, entry to the circuit or pattern, downwind, base, final, departure and clearing the runway. The exact sequence depends on local procedure and aircraft type; our guide to traffic-pattern positions and sequencing shows where those reports fit.
Do not replace a proper position report with Any traffic in the area, please advise. That phrase gives other pilots no useful position or intention and can generate several simultaneous replies. CTAF calls support visual separation; they do not appoint one pilot as a controller or give anyone priority.
Why can I hear ATIS but nobody answers on CTAF?
Hearing ATIS proves only that the receiver and broadcast frequency are working. Silence on CTAF may mean there is no nearby traffic, other pilots are not transmitting, or the simulator does not model interactive CTAF audio.
If expected calls are missing, verify the published frequency, active COM radio, audio-panel selection, radio volume and push-to-talk assignment. Also confirm that you have not confused CTAF with ATIS, AWOS, UNICOM or an inactive tower frequency. Even with no reply, continue making appropriate reports and scan visually for traffic.