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FGCom-mumble simulates radio communication based on the VoIP software Mumble. It integrates fully with the radio stack of your FlightGear plane, allowing you to communicate with other pilots and airspace controllers during your flight. It simulates a global, continuous radio frequency spectrum.

FGCom-mumble is an alternative to the already known FGCom client.

FGCom-mumble leverages the plugin mechanism introduced by Mumble 1.4.0 and just needs a precompiled plugin loaded by a stock Mumble client. You can download the latest release from https://github.com/hbeni/fgcom-mumble/releases.

Caution  The plugin relies on Mumble 1.4.0 which is not yet released.

To test FGCom-mumble, you thus need to self compile Mumble and Murmur (or prebuilt binarys).

Note  This is currently in development and has no stable release for productive use yet. Expect lots of bugs! But please, help testing if you can.
FGCom-mumble logo
Developed by Benedikt Hallinger
Initial release 0.1.0-alpha (08.06.2020)
Latest release see release page
Written in C++, Lua, Java, PHP
OS Windows, GNU/Linux
Development status Active
Type Radio/Communication
License GNU General Public License v3


  • The main FGCom-mumble test server is mumble://fgcom.hallinger.org/fgcom-mumble
  • The status page for that service showing all connected clients is at: http://fgcom.hallinger.org/

Project main goals

  • Provide communication with geographic and channel separation
  • Provide a realistic radio simulation
  • Ease of use for the end user/pilot
  • Arbitrary frequency support
  • ATIS recording and playback
  • Radio station broadcast support
  • Landline/Intercom support
  • RDF detection for clients
  • Ease of server side installation and operation
  • Standalone nature (no dependency on FlightGear)
  • Capability to be integrated into FlightGear, with the option to support third party applications (ATC, but also other flight simulators)
  • Modularity, so individual component implementations can be switched and its easy to add features
  • Good and complete documentation

Installation and setup

The latest release can be fetched from GitHub.

The provided README has detailed instructions on the needed prerequisites and installation procedures.

In short:

  • Have a stock Mumble client >= 1.4.0 running, and load the plugin (mumble settings/plugins page)
  • Join a channel named `fgcom-mumble`
  • Install the FlightGear protocol file (at $FG ROOT/Protocols/)
  • Start FlightGear with the new protocol active (add to launcher: --generic=socket,out,10,localhost,16661,udp,fgcom-mumble)
  • Start using your plane's radio stack (it uses default FGCom buttons, see below)


FlightGear's FGCom-mumble protocol uses the default FGCom buttons: When you want to talk on COM1 you have to press Space. While transmitting you can not hear other pilots trough the used radio (they are half-duplex). You can also talk on COM2 by pressing Shift+Space.

If you want to try it out without FlightGear, you can also start the supplied RadioGUI.

How to test your setup?

First, make sure Mumble is working reliably by talking to other people. Either disable the plugin, or be sure you are outside any radio channel (starting with `fgcom-mumble`).

The plugin alters Mumble's audio stream. It adds static noise depending on the radio signal quality, or cancels out all audio when not in range.

If the server supports it (in essence there is a bot-manager running and a `fgcom-radio-bot` listening) you may do a traditional echo test by tuning `910.00` and start to talk. The radio bot will record that and spawn an echo bot at your position, replaying your message.


For troubleshooting, refer to the projects README as it has further suggestions.


FGCom-mumble supports the legacy FGCom UDP protocol and thus should be compatible to clients supporting that. However, it also features some new UDP fields.

  • FlightGear is supported through a new XML protocol file. This assumes the default radio implementation and works with at least the C172P and the C182S.
  • ATC-pie has built in support already.
  • OpenRadar currently supports just COM1 (ticket pending). To use COM2 and more, you need to either start several mumble instances, or use FGCom-mumble's RadioGUI.
There is a patched version of OpenRadar with FGCom-mumble and 8.33 channel tuning support available here: https://github.com/hbeni/openradar/releases/


The FGCom-mumble RadioGUI is a small Java 11 application that can send the FGCom-mumble UDP messages to the Mumble plugin.

Inside the GUI, you can pick your location from a map and then setup your radio stack.

Server side

By design, all that is needed is a standard Murmur server (version 1.4.0 or later) and a specially named channel (it has to start with `fgcom-mumble`). This is enough to let the plugin do its work. The entire channel is treated as a single, worldwide continuous radio frequency spectrum.

Additional features are implemented using server side Lua bots (which may run somewhere else):

  • ATIS recording and broadcasting
  • Status page data collection

A status page showing client details is available as a PHP website, that gets its data fed from the fgcom-status-bot.

Detailed installation and operation documentation is shipped with the releases, but is also online.

Related content

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