FlightGear keeps crashing? Isolate graphics drivers, preferences, add-on aircraft, scenery and TerraSync faults with this practical fix list.
FlightGear usually keeps crashing because of a graphics driver or OpenGL problem, an overloaded graphics setting, damaged preferences, faulty add-on aircraft or scenery, or an incomplete TerraSync download. Start with a default aircraft and airport, reset FlightGear’s settings, disable custom content and TerraSync, then update the GPU driver and lower rendering options.
What usually causes FlightGear crashes?
The point at which FlightGear crashes is the quickest way to narrow down the cause.
| When it crashes | Likely cause | First test |
|---|---|---|
| Before the cockpit appears | Damaged preferences, incompatible core data, graphics initialisation or driver failure | Reset the user settings and start with basic rendering |
| While loading terrain | Broken custom scenery, an incomplete TerraSync tile or a scenery search-path conflict | Disable TerraSync and remove custom scenery paths temporarily |
| Only with one aircraft | Incompatible aircraft files, scripts or dependencies | Load a bundled default aircraft |
| When the 3D view opens | OpenGL, shader, graphics-memory or rendering-pipeline problem | Update the GPU driver and reduce rendering options |
| After several minutes | Memory exhaustion, driver instability, overheating or a background feature | Monitor memory and temperatures, then disable traffic, weather and network features |
If FlightGear exits before reaching a usable simulation session, our startup checks for a FlightGear installation that will not load cover launcher and installation failures in more detail.
How do I stop FlightGear from crashing?
The fastest fix is to establish a clean baseline and reintroduce features one at a time.
- Record where the crash happens. Note the selected aircraft, airport, rendering mode and final visible loading message. Change one variable at a time; altering everything together hides the actual fault.
- Run a minimal default flight. Select a bundled aircraft and an airport covered by complete installed scenery. Temporarily disable custom add-ons, multiplayer, live weather, AI traffic and TerraSync. If this works, the core simulator is probably sound.
- Reset FlightGear’s user state. Close the simulator and use its reset-to-defaults facility if your launcher provides one. Otherwise, rename rather than delete the per-user settings and cache folders so FlightGear creates clean replacements. Their locations vary by operating system and package type. Back up controller bindings and saved flights before doing this.
- Fix the OpenGL and GPU setup. Install a full graphics driver intended for the installed GPU, restart the computer and make sure a laptop is assigning FlightGear to the dedicated GPU where available. Remote-desktop sessions can expose an inadequate software renderer, so test locally. Our hardware, OpenGL and GPU-selection checks explain the relevant limitations.
- Use conservative graphics settings. Select the basic rendering path and reduce shadows, anti-aliasing, cloud detail, visibility distance and texture demands. If FlightGear becomes stable, restore settings individually until the failing option or memory limit becomes clear.
- Check that the programme and core data match. The FlightGear executable and its data package must come from the same release. A manually configured
FG_ROOTorFG_SCENERYvariable can silently point a new executable at an older data tree. Multiple installations can cause the same problem. - Remove add-on aircraft from the test. An aircraft built for a different FlightGear release may load partially and then fail when its model, instrument or Nasal scripts run. Remove its search path, restart FlightGear and test a bundled aircraft before reinstalling add-ons individually.
- Test scenery and TerraSync separately. If the crash occurs over one region, disable custom scenery and TerraSync. Rename the TerraSync cache if necessary so it can be rebuilt, and confirm that its storage location is writable and has free space. Follow our correct scenery folder and TerraSync setup before restoring custom packages.
- Rule out audio and controller faults. Disconnect non-essential USB controls and start with the operating system’s default audio device. If the launcher permits it, test once with sound disabled. A crash that disappears can then be isolated to a device, driver or custom controller definition.
Once the default flight is stable, restore one aircraft, scenery path or feature per launch. A mistake we see constantly is copying the entire old configuration back at once, which simply restores the original fault.
Why does FlightGear crash only at one airport or with one aircraft?
A location-specific crash normally implicates scenery, while an aircraft-specific crash normally implicates that aircraft package.
- One airport or geographic area: suspect a malformed terrain object, duplicate scenery layer, incomplete download or stale TerraSync tile. Check whether the crash follows the location when using a bundled aircraft.
- One aircraft: suspect incompatible scripts, missing model assets or a package intended for another FlightGear release. Check whether the same airport works with a bundled aircraft.
- Only that aircraft at that airport: test both independently. A complex aircraft may merely push graphics memory over its limit when combined with detailed scenery.
What do FlightGear crash log messages mean?
The useful clue is usually in the final group of console or log messages before the crash, not necessarily the last line alone.
OpenGL,GLSL, shader or context errors point towards the graphics driver, GPU selection or rendering mode.bad_allocor out-of-memory messages indicate exhausted system or graphics memory. Lower scenery and texture demands and close memory-heavy applications.Nasalmessages naming an aircraft path suggest an aircraft script problem, although some Nasal warnings are non-fatal.BTG,STG, terrain or TerraSync errors suggest a damaged or missing scenery tile.- OpenAL or audio-device errors justify a test with sound disabled or a different default output device.
- A segmentation fault or access violation identifies the type of failure, not its cause. Inspect the preceding messages for the affected aircraft, scenery, graphics or library component.
Depending on the build, the launcher may expose a log panel or write a log file. Starting the same FlightGear executable from a terminal can also preserve console output that disappears when the window closes.
Will reinstalling FlightGear fix repeated crashes?
Reinstalling helps when programme files or core data are damaged, but it will not usually remove defective user preferences, caches or add-ons.
Before reinstalling, rename those user-data locations and test a fresh profile. If a clean baseline still crashes, remove the old programme installation, install one matching executable-and-data package, and launch it before restoring anything. Do not combine files from different package methods or releases.
If a clean installation still produces OpenGL failures, remove any CPU or GPU overclock and check whether other 3D applications also fail. Crashes across several applications point towards the graphics driver, operating system or hardware rather than FlightGear itself.