What is Unicom in Aviation?
The aviation industry is filled with a vast array of abbreviations and terms, but what is unicom in aviation? To answer this question, it’s essential to understand what unicom stands for, its purpose, and its significance in the world of aviation.
What Does Unicom Stand For?
Unicom is an abbreviation for Universal Integrated Communication. It refers to a system of voice communication services that are available to aviators, specifically for low-power, ground-based voice communication systems.
Unicom vs. ATIS and ATC
For those new to aviation, it’s crucial to understand the difference between unicom, ATIS (Automated Terminal Information Service), and ATC (Air Traffic Control).
- ATIS: Automated Terminal Information Service (ATIS) is a continuous transmission of recorded information broadcast by an automated voice system to inform pilots about weather, airport conditions, and any other important information related to the airport or airfield.
- ATC: Air Traffic Control (ATC) is the authority responsible for the safety and efficiency of air traffic. They guide pilots from departure to destination, while ensuring safe separation between aircraft.
- Unicom: Unicom is an alternate communication system, often used when ATIS and ATC services are unavailable. It provides voice communication between pilots and air traffic services, including clearance delivery, tower, and ground controllers.
Functions of Unicom
Unicom stations offer various functions to facilitate communication between pilots and ground personnel:
• Communication: Unicom provides two-way voice communication between pilots and ground stations.
• Clearances: Pilots can request and receive clearances, such as taxi instructions, departure procedures, and routing information.
• Advise-and-Report: Unicom allows pilots to advise controllers of their aircraft’s intentions and report changes in aircraft status.
• Other Services: Some unicom stations offer additional services like weather information, airport data, and aeronautical charts.
How Does Unicom Work?
Unicom communication is simple and straightforward. Here’s a step-by-step breakdown:
- Calling: Pilots tune in to the designated unicom frequency and wait for an answer.
- Answer: An operator at the unicom station responds to the call.
- Clearance/Advice: Pilots communicate their requests, such as a clearance, advise of intentions, or report their aircraft’s status.
- Acknowledge/Response: The unicom operator acknowledges the pilot’s message and responds with relevant information.
Unicom Frequencies and Coverage
Unicom stations operate on specific frequencies, which can vary depending on the airport or region. In general, unicom frequencies range from 123.025 to 130.625 MHz.
Here is a list of some common unicom frequencies and their approximate coverage:
| Frequency | Coverage |
|---|---|
| 121.950 | USA west coast airports ( approx.) |
| 123.000 | USA central and southern airports (approx.) |
| 122.600 | USA eastern airports (approx.) |
| 130.425 | Alaska, Pacific northwest airports |
Keep in mind that this list is not exhaustive, and frequencies may change. Always consult local authorities or aircraft manuals for the most accurate information.
Benefits and Limitations
Unicom offers several benefits, including:
• Alternative to ATC: Unicom provides a means of communication for aircraft in non-AVCAPS areas, military exercises, or when ATC is unavailable.
• Reliability: Unicom services are generally reliable and resilient, with few disruptions to communication.
• Regional Coverage: Unicom services are often available in regions with limited or no ATC coverage.
However, unicom has some limitations:
• Range and Interference: Unicom signals can be affected by terrain, distance, or interference from other communication devices.
• Staffing: Unicom stations rely on human operators, who may be unavailable or prone to errors.
Conclusion
In summary, unicom in aviation is an essential communication system that offers an alternative to ATC services. Understanding unicom frequencies, coverage, and functionality can ensure smoother communications during flight. As with any system, there are limitations, but the benefits of unicom services make them a valuable asset for aviators.
Remember to consult local authorities or aircraft manuals for specific unicom information and guidelines when flying in different regions.
Resources
- International Civil Aviation Organization (ICAO). (n.d.). Glossary of Unicom Services. Retrieved from https://www.icao.int/Security/docs/unicom_glossary.pdf
- Federal Aviation Administration (FAA). (n.d.). Universal Integrated Communications (Unicom) Guide. Retrieved from https://www.faa.gov/air_traffic/publications/unicom_guide/
