Set up TerraSync in FlightGear, choose a safe cache folder, download scenery on demand, and fix missing tiles, slow loads and path conflicts.
To set up TerraSync in FlightGear, enable automatic scenery downloading in the launcher, choose a writable cache folder with ample free space, then start the simulator while online. TerraSync fetches terrain and objects around your aircraft and stores them locally; revisit an area later and FlightGear normally reads the cached files.
How do I enable TerraSync in FlightGear?
In launcher-based FlightGear installations, TerraSync is controlled by the automatic scenery download setting selected before the simulator starts.
- Open the FlightGear launcher. Find its settings or configuration area and look for an option labelled Download scenery automatically, Automatic scenery download or TerraSync. The wording and location vary between launcher versions.
- Enable automatic downloading. Leave it enabled whenever you want FlightGear to fetch uncached scenery during a flight.
- Select a dedicated cache folder. Choose a writable local folder with plenty of free space. Avoid the FlightGear application directory, protected system folders and removable drives that may not always be connected.
- Start at the required airport while online. TerraSync begins fetching the surrounding scenery after FlightGear starts. The first visit to an area can take longer because nothing has been cached yet.
- Restart the flight if necessary. If the aircraft loads before its local tiles arrive, restarting at the same location after the download has progressed often clears ocean tiles or incomplete terrain.
For a launcher-free start, FlightGear provides the command-line options --enable-terrasync and --terrasync-dir=/absolute/path/to/TerraSync. Quote a path containing spaces according to your operating system's command syntax.
What does TerraSync download?
TerraSync downloads FlightGear world-scenery data near the aircraft and keeps those files in its cache for later flights.
This can include terrain, placed objects and available building data. It is not live satellite imagery, and it does not install aircraft or guarantee the bespoke detail found in a custom airport package. Sitting at one airport also does not download the whole world.
| Scenery method | Choose it when | Main trade-off |
|---|---|---|
| TerraSync | You normally fly online and visit many regions | The first visit needs time and bandwidth; the cache grows with use |
| Manual regional scenery | You need a particular airport, mesh or customised region | You must manage folders, updates and scenery priority |
| Pre-downloaded world scenery | You fly offline or cannot depend on downloads during flight | It requires considerably more storage and manual maintenance |
TerraSync and manual packages can coexist. Our guide to installing and prioritising FlightGear scenery explains how to arrange their search paths without one unexpectedly masking another.
Why is TerraSync enabled but scenery still missing?
When TerraSync is enabled but FlightGear still shows ocean, flat terrain or missing objects, the usual causes are an unfinished download, an unwritable cache or a scenery-path conflict.
- Allow for the initial download. A first-time location may load before all nearby files have arrived. Keep FlightGear running while online, then restart at the same airport.
- Check the cache folder. Confirm that files are being created or modified there. If nothing changes, select another local folder for which your user account has read and write permission.
- Check free space. TerraSync's cache expands as new regions are visited. A full drive can leave incomplete or unusable tiles.
- Inspect FlightGear's log. Search for messages containing
TerraSync,HTTP,permissionorfailed. These distinguish a network failure from a folder or path problem. - Check security and network restrictions. A firewall, proxy or security tool may permit FlightGear itself while blocking its scenery requests.
- Review scenery priority. An older manual package placed ahead of TerraSync can mask newer downloaded terrain. Keep custom scenery ahead only when it is intended to override TerraSync.
A mistake we see often is repeatedly deleting the cache before finding the real fault. Instead, close FlightGear, point TerraSync at a new empty test folder and revisit one airport. If that works, the original cache or its permissions were the problem; if it does not, concentrate on the network and launcher settings.
Where is the TerraSync cache, and can I move it?
The TerraSync cache is the download folder shown in FlightGear's launcher settings; its default location varies by operating system, package and launcher version.
Use the launcher's folder control or the startup log to identify it rather than relying on a generic path from another installation. To move it, close FlightGear, move the complete directory without changing its internal hierarchy, select the new location in the launcher and test a previously downloaded airport.
You can delete the cache while FlightGear is closed, but every removed area must be downloaded again. Keep manual add-on scenery in separate directories so that clearing TerraSync cannot erase it accidentally.
Can TerraSync download an entire route for offline use?
TerraSync caches scenery around the active aircraft, not a guaranteed corridor covering the complete flight plan.
Loading the departure while online generally prepares only that vicinity. For an offline flight, visit and cache the departure, arrival and relevant en-route areas beforehand, or use a manually installed package. A pre-downloaded HD world scenery package is the more dependable choice when continuous internet access is unavailable.
Does TerraSync replace manually installed scenery?
No; TerraSync is an on-demand source for FlightGear's published world scenery, while manual packages remain useful for offline coverage, specialised terrain and detailed custom airports.
We recommend keeping TerraSync in its own cache and each manual package in a separate directory. This makes path priority clear, simplifies troubleshooting and prevents one scenery source from being overwritten while another is updated.