What Is UNICOM? Airport Advisory Frequencies Explained

UNICOM is a privately operated, non-government air-to-ground radio station found at many airports without an operating control tower. It gives pilots advisory information — wind, the runway in use, traffic, and field conditions — plus services like fuel and parking. UNICOM is not air traffic control and cannot issue clearances or instructions. That last sentence is the one that trips up most student pilots, so let’s plant it early and build from there.

When you fly into a small field with no tower, nobody is in charge of the airspace the way they are at a busy Class C airport. There’s no controller sequencing you, no one telling you which runway to use. Instead, you rely on a shared frequency, your own eyes, and a person on the ground who may — or may not — pick up the mic. That’s UNICOM, and learning to use it well is one of the most practical skills you’ll carry from your first solo all the way to your hundredth cross-country.

What is UNICOM and what does it do?

UNICOM is a non-government, FCC-licensed air-to-ground communication station, usually operated by a fixed-base operator (FBO), flight school, or airport manager. Per the AIM Pilot/Controller Glossary, it provides airport advisory information at locations without a control tower or where a tower is closed — things like the active runway, surface wind, and known traffic — plus ground services such as fuel, parking, and a courtesy car.

The key word is advisory. A UNICOM operator is often a line person fueling airplanes or a dispatcher answering the phone. They’re doing you a favor by relaying what they can see and what other pilots have reported. They are not watching radar, and they cannot sequence traffic.

UNICOM also doubles as your link to airport services. Calling ten miles out for fuel or to ask the operator to flip on the pilot-controlled lighting is exactly what the station is there for. Think of it as the airport’s front desk, reachable from the cockpit.

The Aeronautical Information Manual covers all of this in AIM 4-1-9, Traffic Advisory Practices at Airports Without Operating Control Towers, which lays out how UNICOM, CTAF, and self-announce procedures fit together at non-towered fields.

What’s the difference between UNICOM, CTAF, and MULTICOM?

CTAF stands for Common Traffic Advisory Frequency — the single frequency designated for carrying out airport advisory practices while operating to or from an airport that does not have an operating control tower. UNICOM and MULTICOM are types of station or frequency that can serve as the CTAF. So CTAF is the role; UNICOM and MULTICOM are players that can fill it.

Here’s how it shakes out at different airports. If the field has a UNICOM, that UNICOM frequency is usually the CTAF. If there’s no UNICOM at all, pilots use MULTICOM on 122.9 MHz. At a part-time tower airport, the CTAF when the tower is closed is often the tower frequency itself, or a published Flight Service frequency.

The practical takeaway: you find the correct CTAF on the sectional chart or in the Chart Supplement, then you broadcast on it. Whether a human answers depends on whether that CTAF happens to be a staffed UNICOM.

What UNICOM frequencies should I expect?

The most common UNICOM frequencies are 122.700, 122.725, 122.800, 122.975, 123.000, 123.050, and 123.075 MHz. You’ll see one of these published in the airport’s frequency box on the sectional and in the Chart Supplement. MULTICOM, used where there is no UNICOM, is 122.9 MHz.

Don’t memorize a single number and assume it works everywhere. Two airports twenty miles apart can use different UNICOM frequencies, and a busy training area might have several fields sharing one frequency — which is exactly why your radio calls need to start with the airport name (more on that below).

Always pull the current frequency from an official source before you fly. Frequencies change, and the Chart Supplement (formerly the Airport/Facility Directory) is the authoritative reference. A frequency you scribbled on a kneeboard last summer may be stale.

How do I make a UNICOM radio call?

A good non-towered radio call follows the same four-part structure every time: who you’re calling, who you are, where you are, and what you intend to do — then you close by repeating the airport name. The AIM recommends this self-announce format so every pilot listening can build a quick mental picture of the traffic.

For example, inbound to a field called Pine Creek: “Pine Creek traffic, Cessna Eight-Five-Two-Charlie-Papa, ten miles south, inbound for landing, Pine Creek.” Entering the pattern: “Pine Creek traffic, Skyhawk Two-Charlie-Papa, entering left downwind runway one-eight, Pine Creek.” Notice the airport name bookends the call. That’s deliberate — it tells pilots at the other field on the same frequency that this transmission isn’t about them.

Keep it short. Use plain position and intentions, not a life story. And remember you’re talking to two audiences at once: the UNICOM operator, who might give you an airport advisory, and every other airplane in the area, who is using your call to stay clear of you.

AIM 4-1-9 publishes recommended points for when to self-announce — inbound roughly ten miles out, then again entering downwind, base, and final, and once more when you clear the runway. Build the habit of calling early and often rather than guessing the exact mileage; being predictable matters more than being precise to the tenth of a mile.

Can UNICOM clear me to land or take off?

No. UNICOM cannot clear you to do anything. It is a non-government advisory station with no air traffic control authority. A UNICOM operator can tell you “favoring runway two-seven, wind two-five-zero at eight, one in the pattern,” but the word “clear” never carries regulatory weight from a UNICOM. Only an operating control tower issues clearances.

This is the single most important concept in this article. At a non-towered airport you are the final authority on the safe operation of your aircraft. If the UNICOM operator suggests runway nine but you can plainly see a stronger wind favoring runway two-seven, you fly the runway that’s safe. The operator isn’t looking out your window.

The same goes for traffic. UNICOM might report “no known traffic,” but “no known” is not “no traffic.” Plenty of airplanes fly without radios, or with the wrong frequency dialed in. Your eyes outside the cockpit are the real traffic-separation system at a non-towered field. Advisories supplement your scan; they never replace it.

If you’re early in your training and want this kind of airspace and communications foundation built the right way from day one, our free Total Student Pilot course walks you through how non-towered operations actually work before you ever key the mic.

What if nobody answers on UNICOM?

If you call UNICOM and get silence, that is completely normal. Many UNICOM stations are unattended, part-time, or simply too busy to answer. When that happens, you switch to self-announce: you broadcast your position and intentions “in the blind” on the CTAF so any nearby traffic can hear you, even though no ground operator responds.

Self-announcing is not optional just because the FBO is closed. AIM 4-1-9 specifically recommends that pilots continue to announce on the CTAF when an FSS or UNICOM is unavailable. Your calls are still doing their main job — keeping other airplanes informed — even when no human on the ground is listening.

Use other clues to fill the gap a UNICOM operator would normally provide. A windsock, tetrahedron, or wind tee tells you the favored runway. Listen for other pilots’ calls to learn which runway is in use. And when in doubt, an overflight above pattern altitude to look at the windsock and the traffic flow is a perfectly legitimate, safe way to gather the picture yourself.

A real lesson from an Alaska airstrip

I learned the “advisory, not authority” lesson cold one winter morning on a gravel strip up in Alaska. I was flying a Cessna 172, called UNICOM ten miles out, and a friendly voice came back: “favoring two-six, calm wind.” Easy day, I thought. I set up for two-six.

Except the windsock told a different story. As I got closer it was standing nearly straight out, and not from the direction that operator described — the wind had shifted while he was pouring coffee. If I’d taken his advisory as gospel, I’d have flown a downwind approach into terrain that does not forgive that mistake. I circled, looked, and landed the other way.

Nothing dramatic happened, because the system worked exactly as designed: the operator gave me his best information, and I — the pilot in command — checked it against what I could see and made the call. That’s the whole point of UNICOM. It’s a teammate handing you data, not a controller handing you instructions. Aviation education since 2006 and instructing as a CFI since 2017 has shown me the same pattern again and again: the pilots who stay safe at non-towered fields are the ones who treat every advisory as a starting point, then verify with their own eyes.

If you want that mindset trained in properly — radio work, non-towered procedures, and real-world decision-making — our Private Pilot Ground School builds it module by module so you show up to the airport day-one ready, not just checkride ready.

PLT Study Guide

The FAA tags knowledge-test questions with PLT (Pilot Learning Statement) codes. For UNICOM and non-towered communications, these are the codes that actually match the content — study them in plain English:

Study point on PLT146: Most UNICOM exam questions live here. The FAA wants you to know the self-announce procedure and recommended traffic-pattern communication for an airport without an operating control tower. If a question asks what frequency to use or when to broadcast inbound, it’s testing PLT146.

Study point on PLT044: Watch for questions that try to make a UNICOM advisory sound like a clearance. The correct answer always preserves the pilot’s authority — UNICOM informs, ATC instructs.

Frequently Asked Questions

FROM CHRIS

Master UNICOM and you’ve unlocked a huge chunk of real-world flying: every quiet country strip, every closed-tower arrival, every cross-country stop where it’s just you, the radio, and your own good judgment. Get comfortable calling early, listening hard, and verifying advisories with your eyes, and non-towered airports stop feeling like the Wild West and start feeling like home.

Throttle On!

Chris Palmer

Founder & Chief CFI, Angle of Attack — Two-Time Master Aviation Educator and Gold Seal CFI