How do I fix FSX crashing when I select Free Flight?

FSX and FSX: Steam Edition usually crash when Free Flight is selected because the active configuration, default saved flight, weather file, logbook, aircraft, scenery or start-up add-on is damaged or incompatible. Test a stock aircraft at a stock airport, then reset each user file separately until the failing component is identified.

Where does the FSX Free Flight error happen?

The point at which FSX closes identifies which part of Free Flight is failing.

If the aircraft reaches the cockpit and FSX closes later, Free Flight has loaded successfully. Use our diagnosis for recurring FSX crashes after a flight has started instead.

Is this an FSX software crash or a simulated plane crash?

An FSX software crash closes, freezes or stops fsx.exe; an aircraft crash inside the simulator leaves FSX running.

If FSX displays Aircraft crashed after an impact and offers to reset or end the flight, crash detection is working normally. Changing realism or crash-detection settings affects that simulated plane crash, but it will not fix Free Flight closing to the desktop.

How do I fix an FSX Free Flight crash?

The reliable Free Flight fix is to establish a clean stock flight, then restore one configuration file or add-on at a time.

1. Back up the user files. Close FSX and copy the active configuration folder and your Documents\Flight Simulator X Files folder somewhere safe. The configuration is normally under %APPDATA%\Microsoft\FSX; some side-by-side Steam Edition installations use %APPDATA%\Microsoft\FSX-SE.

   Keep these copies outside the FSX installation directory. Renaming is safer than deleting because every change can then be reversed.

2. Try a completely stock flight. If the Free Flight screen opens, select the stock Cessna 172, an airport unaffected by add-on scenery and a standard weather theme. Do not load a saved flight. Temporarily set AI traffic to zero if the crash occurs during loading.

   If this stock-flight test works, the core simulator can run. Restore the original aircraft, airport, weather and traffic separately to identify which choice triggers the crash.

3. Rebuild the active fsx.cfg. With FSX closed, enter %APPDATA%\Microsoft\FSX in File Explorer and rename fsx.cfg to fsx.cfg.old. Check the FSX-SE folder as well if both boxed FSX and Steam Edition have been installed; the file with the latest modification time after an FSX session is usually the active one.

   Restart FSX and allow it to create a clean configuration. Do not copy old graphics tweaks or trusted-software entries back yet. A mistake we see often is editing an fsx.cfg copy in the installation directory rather than the active file in the Windows user profile.

4. Remove the saved start-up flight and weather from the test. A user-created .FLT file can retain references to an aircraft, airport, panel or scenery product that has since been removed. Move the suspect .FLT and its matching .WX file out of Documents\Flight Simulator X Files, then start a new flight from the menu.

   If the crash continues, rename Logbook.BIN in that folder to Logbook.BIN.old. FSX should create a new logbook while the original remains available for recovery.

5. Disable start-up modules separately. A new fsx.cfg does not disable programs loaded through dll.xml or exe.xml. In the active AppData configuration folder, rename one of these files with an .old suffix, test FSX, then test the other.

   If one file is responsible, restore it and disable its add-on entries in small groups. Keep the XML structure valid. Our add-on isolation checks for aircraft, gauges, scenery and start-up modules explain how to narrow down several possible culprits without removing everything at once.

6. Test the selected aircraft and scenery independently. Load the suspect aircraft at a stock airport, then load a stock aircraft at the suspect airport. Disable rather than delete the latest aircraft or scenery package, and restart FSX after changing the Scenery Library.

   When many add-ons could be responsible, disable half, retest and repeat with the failing half. This finds a bad component much faster than uninstalling packages randomly.

7. Read the Windows faulting-module entry. In Event Viewer, open Windows Logs and Application, then find the error recorded for fsx.exe at the time of the crash. A named third-party gauge or module is a strong lead.

   ntdll.dll and KERNELBASE.dll often identify where the failure surfaced rather than its original cause. Likewise, SimProp.dll or VisualFX.dll can be triggered by faulty aircraft, effects or scenery; use our checks for SimProp and VisualFX fault reports before replacing core DLLs.

   If UIAutomationCore.dll appears and the crash happens while opening menus, treat it as a menu-interface fault. Do not copy an arbitrary replacement DLL into FSX based solely on the module name.

8. Repair core files last. Steam Edition users can verify the installed files through Steam. Boxed-edition users can run the repair option supplied with their installation media.

   File verification can restore altered stock files, but it does not reset damaged AppData settings, saved flights or most third-party content. Never mix boxed-edition DLLs with Steam Edition files.

Why does only one aircraft or airport crash FSX?

A Free Flight crash tied to one selection usually belongs to that aircraft, airport or one of its dependencies, not to the Free Flight feature itself.

• Only one aircraft fails: suspect its model, panel, compiled gauges, effects, textures or aircraft.cfg. Confirm that a stock aircraft loads at the same airport.
• Only one airport fails: suspect local scenery, a duplicate airport definition or a missing object library. Test the same aircraft at a distant stock airport.
• Only one aircraft-and-airport combination fails: the products may conflict, or their combined textures, gauges, scenery and traffic may exhaust FSX's available memory.
• Every stock combination fails: return to fsx.cfg, saved-flight, start-up-module and core-file checks instead of reinstalling individual add-ons.

Can a WeatherFile or .WX file cause the Free Flight error?

A damaged or obsolete saved-weather file can cause a Free Flight error when FSX attempts to restore the flight that references it.

Saved flights commonly use a matching .FLT and .WX pair. Move both user-created files out of Documents\Flight Simulator X Files and select a standard weather theme for the test. Do not delete stock weather files or copy an unrelated weather file into the FSX installation.

If standard weather works, restore the saved flight without its old weather or recreate the flight from scratch. This is particularly relevant when the original weather file came from an add-on that is no longer installed.

Can Free Flight shut down because FSX runs out of memory?

Memory pressure is likely when simple stock flights load but detailed aircraft, large airports, dense traffic or complex weather make FSX close during loading.

FSX remains a 32-bit application on 64-bit Windows, so installing more system RAM does not remove its per-process address-space limit. Repeat the same flight with a stock aircraft, zero AI traffic, standard weather and reduced scenery complexity. If that works, reduce the heaviest component rather than continuing to reset configuration files.

What changes for FSX: Steam Edition?

FSX: Steam Edition uses the same troubleshooting logic, but its active configuration folder and core-file repair method can differ from boxed FSX.

A Steam-only installation may use the FSX AppData folder, while a machine that has also held boxed FSX may use FSX-SE. Do not assume the folder name: launch and close FSX, then check which configuration file received the new modification time.

Steam verification should follow the user-file and add-on tests because it does not remove a corrupt saved flight or reset dll.xml. If Steam Edition also fails before or during its opening screens, follow our Steam-specific sequence for configuration, modules, scenery and file verification.

Should I reinstall FSX?

Reinstall FSX only after stock content still fails with a new configuration, no custom saved flight, disabled start-up modules and repaired core files.

A normal reinstall can leave fsx.cfg, saved flights, the logbook and third-party add-ons untouched, causing the same Free Flight crash to return. Preserve those folders, test the base simulator before restoring anything, and keep boxed FSX and Steam Edition files separate.