Learn how to run FlightGear as a portable installation from a ZIP or external drive, keeping settings, scenery and TerraSync in one place.
Yes. FlightGear can run as a portable installation by extracting its ZIP package to a writable folder or external drive and launching it there. To make it genuinely portable, keep scenery, downloaded aircraft, TerraSync data and the user-data directory on that drive; otherwise FlightGear may still write settings and cache files to the host computer.
How do I make FlightGear fully portable?
Use the archive build and redirect FlightGear's writable data paths before opening the Launcher for the first time.
- Download the archive package. Our FlightGear download with an extractable ZIP package is better suited to portable use than a conventional installer. Choose a build compatible with the host operating system and processor.
- Extract the whole archive. Put it in a writable folder on an internal disk, external SSD or USB drive. Do not run FlightGear from inside the ZIP, and preserve the supplied directory structure.
- Create separate writable folders. Useful names include
UserData,Downloads,SceneryandAircraft. These names are not mandatory; keeping them separate simply makes updates and fault-finding easier. - Redirect
FG_HOME. Set theFG_HOMEenvironment variable to the portableUserDatafolder before starting FlightGear or its Launcher. This is where preferences and other user-specific state should be written. - Set the content paths. Select the portable download and scenery folders in the Launcher. Command-line users can use options such as
--download-dir=pathand--fg-scenery=path. The extracted package should normally find its own base data; use--fg-root=path-to-dataonly if it cannot. - Test the installation. Change a harmless preference, close FlightGear and confirm that files were created or updated inside the portable user folder. Then start it again with the drive mounted under a different path if that is likely to happen in normal use.
A startup script is safer than saved absolute paths when a removable drive may receive a different drive letter. On Windows, a batch file can derive paths from %~dp0; on Linux or macOS, use the script's own directory as the base. Set FG_HOME in that script before invoking FlightGear.
Copying an existing installed program directory sometimes works, but it may omit preferences, downloaded content and paths stored under the original user account. Starting with the ZIP package produces a cleaner portable installation.
FlightGear folders to keep on the portable drive
A self-contained copy needs the complete application package plus every folder that FlightGear writes to or searches for additional content.
| Content | Portable location | Key point |
|---|---|---|
| Application and base data | Extracted package folder | Keep directories such as the executable and base data folder in their supplied structure. |
| Preferences and user state | Folder assigned to FG_HOME | Redirect this before the Launcher starts, not after settings have already been written to the host profile. |
| TerraSync and downloaded content | Portable download directory | Set the Launcher download location or use --download-dir. |
| Manual scenery and aircraft | Separate Scenery and Aircraft folders | Add these locations to FlightGear's search paths rather than modifying the base package. |
Keep a separate writable user-data folder for each major FlightGear release. Sharing one FG_HOME between substantially different releases can carry incompatible saved preferences into the newer or older copy.
Can portable FlightGear run offline?
Yes, FlightGear runs offline when the aircraft, navigation data and required scenery are already stored locally.
TerraSync cannot fetch missing terrain without a connection, and online weather and multiplayer services will be unavailable. Before travelling, load the intended airports and route while connected or follow our guidance for keeping FlightGear scenery in manually selected and offline folders.
Scenery contains many small files, so a cheap USB flash drive can cause pauses while terrain loads. An external SSD is the better choice for a large TerraSync repository. Leave enough free space for new tiles and ensure the drive is writable.
Why does a portable copy lose settings or scenery?
Most portable FlightGear failures come from incorrect paths, changing drive letters or write permissions rather than the simulator requiring installation.
- Settings appear on the host computer:
FG_HOMEwas not set before FlightGear or the Launcher started. Correct the startup script, then copy any wanted preferences into the portable user folder after making a backup. - FlightGear cannot find base data: the archive structure was changed or
FG_ROOTpoints to the wrong directory. It must identify the extracted base-data folder containing FlightGear's core files, includingdefaults.xml. - Terrain is missing or replaced by water: the scenery path is wrong, the drive letter changed, or the required TerraSync tiles were never downloaded.
- Changes are not saved: the portable directory is read-only, storage is full, or the host's security policy blocks writing or running executables from removable media.
- Paths break on another computer: the Launcher saved an absolute path such as a specific Windows drive letter. Use a location-aware startup script or update the paths after mounting the drive.
Will the same portable copy run on every computer?
No. A portable package avoids installation, but its executable still has to match the host operating system and processor, and the computer must satisfy FlightGear's graphics and memory requirements.
A Windows build does not become a macOS or Linux application because it is stored in a ZIP. Check the destination machines against our FlightGear platform and hardware requirements, including graphics-driver support and available storage.
Controller assignments, display settings and rendering options may also need different profiles on machines with different hardware. Even after all FlightGear paths are redirected, the operating system may retain recent-file records, temporary files or security metadata, so portable should not be interpreted as a guaranteed zero-trace mode.