UNICOM

Updated at: 2025-12-06 08:40
UNICOM is a non-government, privately operated ground radio station that provides advisory information to pilots at an aerodrome, most often one without an operating control tower. Understanding how and when to use UNICOM is essential for safe operations at non-towered airports and during off-hours at towered fields.

1. Definition of UNICOM

In aviation, UNICOM ("universal communications") is a licensed, privately operated aeronautical advisory station located at or near an aerodrome. It is used primarily at non-towered (uncontrolled) airports to provide pilots with local information such as wind, runway conditions, and other advisory data on request.
Unlike an air traffic control (ATC) tower, a UNICOM station does not issue clearances or exercise positive control over aircraft. It is an advisory service only. Pilots remain fully responsible for separation, traffic avoidance, and compliance with regulations.
In many countries, including the United States, UNICOM is typically operated by the airport’s fixed-base operator (FBO) or another local entity rather than by a governmental air navigation service provider.

2. Purpose of UNICOM

The primary purpose of a UNICOM station is to enhance situational awareness at aerodromes without an operating control tower by providing local, non-control information to pilots on request.
Typical information a UNICOM operator may provide includes:
  • Surface wind direction and speed (if known)
  • Runway in use and runway surface condition (dry, wet, contaminated, closed)
  • Airport advisories (bird activity, vehicles on runway, local procedures)
  • Traffic advisories based on what the operator can see or hear on frequency
  • Availability of fuel, maintenance, and ground handling services
  • Parking instructions and ramp directions
  • Local weather observations, such as visibility or cloud cover, when no official report is available
Because UNICOM is advisory, the information is intended to support pilot decision-making rather than to direct aircraft. Pilots should treat UNICOM reports as one input among others, alongside visual observations, published procedures, and official weather products.

3. Use of UNICOM in aviation

3.1 Relationship to CTAF and other frequencies

At many non-towered aerodromes, the UNICOM frequency also serves as the Common Traffic Advisory Frequency (CTAF), the frequency pilots use to make position and intention broadcasts to each other. In such cases, the same frequency is used both for pilot-to-pilot traffic calls and for contacting the UNICOM operator when available.
However, the terms are not interchangeable:
  • UNICOM refers to the ground station and service.
  • CTAF refers to the function of the frequency as a common traffic advisory channel, regardless of whether a UNICOM operator is present.
In some regions, an aerodrome may have a designated CTAF that is separate from the UNICOM frequency, or may use a different system such as MULTICOM or an aerodrome flight information service (AFIS). Always verify the correct frequency and its purpose in the relevant aeronautical publication or chart supplement.

3.2 Typical student pilot use cases

For a student pilot, UNICOM use is most common in the following situations:
  • Before arrival: obtaining local wind, runway in use, and any special advisories.
  • On the ground: asking about fuel, parking, or preferred taxi routes to the ramp or FBO.
  • During off-tower hours at a controlled field: when the tower is closed and the published UNICOM/CTAF becomes the primary advisory frequency.
Example: A student inbound to a non-towered airport may call UNICOM to ask, "request airport advisory" and then use that information to select a runway and plan the traffic pattern, while still maintaining a proper visual lookout and making standard traffic calls on CTAF.

3.3 Standard call structure to UNICOM

When calling UNICOM, transmissions should be clear, brief, and follow standard radiotelephony structure. A typical call includes:
  1. Who you are calling (airport name + "UNICOM").
  2. Who you are (aircraft type and full or abbreviated call sign, depending on local rules).
  3. Where you are (position and altitude if airborne, or location on the ground).
  4. What you want (type of information or service requested).
Example airborne call: "Springfield UNICOM, Cessna N123AB, ten miles west, three thousand five hundred feet, inbound for landing, request airport advisory."
Example ground call: "Springfield UNICOM, Cessna N123AB at the fuel pumps, request taxi to parking."

4. Operational considerations for student pilots

4.1 Limitations of UNICOM information

UNICOM operators are not required to have complete or up-to-date operational information. They may not have direct access to certified weather instruments, and their view of the traffic pattern or runway may be limited. As a result, all UNICOM information should be treated as advisory and potentially incomplete.
Student pilots should always:
  • Cross-check UNICOM wind reports with visual cues such as windsocks.
  • Verify runway suitability using charts, NOTAMs, and physical observation.
  • Maintain standard traffic pattern procedures regardless of UNICOM comments, unless safety requires deviation.
  • Continue making self-announce calls on CTAF even when UNICOM is active.

4.2 When UNICOM is not staffed

Many UNICOM stations are not staffed continuously. Outside of operating hours, the frequency may be unattended, or it may revert to pilot-to-pilot use only as a CTAF. In some cases, the frequency may key an automated system, such as an Automated Weather Observing System (AWOS) or Automated Surface Observing System (ASOS).
If no UNICOM operator responds:
  1. Assume the station is unattended.
  2. Use the published CTAF procedures for self-announcing your position and intentions.
  3. Obtain weather from AWOS/ASOS or other official sources if available.
  4. Rely on visual cues and standard pattern operations for runway selection and traffic awareness.

4.3 Example arrival procedure using UNICOM

The following sequence illustrates a typical arrival to a non-towered airport with an operating UNICOM. Actual procedures depend on national regulations and local practices, so always follow your training and official guidance.
  1. Before entering the vicinity: Listen on the published UNICOM/CTAF frequency to build a picture of existing traffic.
  2. Initial call to UNICOM: When appropriate, call the aerodrome UNICOM: state who you are, where you are, and request an airport advisory.
  3. Evaluate the advisory: Note reported wind, runway in use, and any hazards. Compare with your own observations and weather data.
  4. Select pattern entry: Choose a standard pattern entry consistent with regulations and local procedures (for example, a 45° entry to the downwind leg for the active runway).
  5. Make CTAF calls: Self-announce your position and intentions on the same frequency, addressing other traffic (for example, "Springfield traffic" rather than "Springfield UNICOM").
  6. Continue visual scanning: Maintain a constant lookout for other aircraft, regardless of what UNICOM has reported.
  7. After landing: Once clear of the runway, you may call UNICOM for taxi or parking guidance if the operator offers that service.

4.4 Radio phraseology tips for students

To communicate effectively with UNICOM, student pilots should:
  • Speak slowly and clearly, avoiding unnecessary words.
  • Use the airport name at the beginning and end of each transmission when appropriate.
  • State altitude and distance when airborne to help others understand your position.
  • Confirm critical information (such as runway in use) by repeating it back in your own words.
  • Avoid asking UNICOM for services it does not provide, such as clearances or separation instructions.

5. Examples of UNICOM use

The following short examples show typical, concise UNICOM exchanges that a student pilot might encounter.
Example 1: Inbound for landing
"Lakeside UNICOM, Piper N456CD, eight miles south at three thousand feet, inbound for landing, request airport advisory."
Possible reply: "Piper Six Charlie Delta, Lakeside UNICOM, wind two four zero at eight, runway two four in use, no reported traffic."
Example 2: Taxi to parking
"Lakeside UNICOM, Piper N456CD clear of runway two four at Alpha, request taxi to parking."
Possible reply: "Piper Six Charlie Delta, taxi straight ahead to the main ramp in front of the FBO."
Example 3: No response from UNICOM
The student calls: "Lakeside UNICOM, Piper N456CD, ten miles east, three thousand feet, inbound for landing, request airport advisory."
No reply is heard. The pilot then treats the frequency as CTAF, continues listening, and makes standard self-announce calls such as "Lakeside traffic, Piper N456CD, entering left downwind runway two four, Lakeside."

Summary

UNICOM is a non-government advisory radio service that supports safe operations at aerodromes without an operating control tower by providing local information on request. For student pilots, effective use of UNICOM involves understanding its advisory nature, using clear and concise radio phraseology, and always combining UNICOM information with visual scanning, standard traffic pattern procedures, and official weather and aeronautical data.