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How to listen to aircraft frequencies

Updated July 20, 2017

Modern scanning radios make listening to a wide variety of public communications an easy and enjoyable hobby. Most modern scanners can receive the commercial aircraft band. Some can receive the military aviation band as well. Most of the radio traffic is routine, as pilots receive instructions from ground controllers, ask permission to move aircraft, or get weather updates. A listener will rarely hear a pilot declare an emergency, though these tense moments happen occasionally.

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Aircraft radios use amplitude modulation (AM) rather than frequency modulation (FM). AM is susceptible to atmospheric noise, such as static bursts from thunderstorms. The advantage of AM is that a listener can hear two simultaneous transmissions on the same frequency. With FM, only the stronger one can be heard. There's less risk of misunderstood communication with AM, which is a safety consideration in crowded air space.

Aircraft frequencies use simplex communication, which means transmitters and receivers are on the same frequency. However, it's not always possible to hear both sides of the conversation, because an aircraft directly overhead may be communicating with a ground station far over the horizon. An external antenna mounted as high as possible will improve reception of weak signals from distant transmitters.

Scanning radios are programmed to change frequencies in discrete steps. In the aircraft band, stations are 25 kHz apart, so the radio scans in 25 kHz steps.

Commercial and private aircraft communications take place in the 108-137 MHz band. The first 10MHz are used for navigation rather than voice contacts. Almost all modern scanners will receive this band.

Military aircraft use two bands: 136-144 MHz and 225-400 MHz. They may be AM or FM. Some radio scanners will receive these frequencies, but many do not. Radio enthusiasts need fast scanners capable of 100 channels per second or more in order to cover the wide range of frequencies.

Find a convenient location for the scanner radio, one that's not in direct sunlight or near a heat source. Overheating is one cause of electronic failures. Follow the radio manual for the programming steps. If there are small children in the house, place the receiver out of their reach, unless you have an urge to reprogram it frequently.

If you install an outside antenna, mount it as high as possible, perhaps in an attic or on the roof. Connect a coaxial cable from the antenna to the rear of the radio. Electronics stores offer these cables in pre-cut lengths with connectors already installed.

One way to find airport frequencies is through a radio guide book. These are available through retailers or online.

Major airports use the Automatic Terminal Information Service (ATIS). This is a continuous broadcast that updates frequently, supplying weather, runway and taxiway information, as well as the frequencies for approach, departure and ground control.

Tip

In a noisy environment, lightweight headphones make transmissions easier to hear.

Warning

If an outside antenna is used, install a lightning arrester to protect people and property. Be sure it conforms to local codes. Never install an antenna where it could contact a power line. Mobile operation of a scanning radio may be restricted or unlawful in some areas.

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Things You'll Need

  • Scanning radio capable of receiving 118-136 MHz (225-400 MHz for military).
  • Outside antenna and coaxial cable -- if greater range is needed or desired.
  • Frequency guide.

About the Author

I'm a professional electronics technician working on commercial aircraft. My main responsibility is the Honeywell Enhanced Ground Proximity Warning Computer, a 486-based machine that uses GPS information to compare aircraft position, speed and altitude against a simplified terrain map of the planet. This is a flight critical system on modern aircraft, but it's not the sole focus of my work. I've done maintenance on aircraft electronics beginning with the largely electro-mechanical systems on 727s and DC-10s, mostly on autopilots but including navigation and communication radios as well. I enjoy explaining technology to people unacquainted with it, and try to write as simply and directly as possible.

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