Why does FSX crash when I select Free Flight?

Microsoft Flight Simulator X (FSX) and FSX: Steam Edition usually crash on selecting Free Flight because a configuration file, default flight, logbook, aircraft or scenery entry is corrupt; an incompatible add-on can do the same. Start with a stock aircraft and airport, then isolate configuration, menu, add-on and memory faults.

Where does the Free Flight crash happen?

The crash point separates a menu fault from a flight-loading fault. Note exactly what you clicked and whether a loading percentage appeared before FSX closed.

How do I stop FSX closing when Free Flight opens?

Work through these checks in order and test FSX after each change. Changing several things at once hides the actual cause and can create a second fault.

1. Back up the user files first. Preserve your configuration, saved flights and add-on XML files before renaming anything. Our guide explains how to make a safety copy of the files that hold your FSX setup and saved flights.

2. Try a stock flight. If the Free Flight screen remains open, select the default Cessna 172, an airport without add-on scenery and a simple clear-weather theme. Do not load a saved flight. Temporarily reduce AI traffic if the crash occurs during loading rather than in the menu.

3. Rebuild fsx.cfg. Close FSX, enter %APPDATA%\Microsoft\FSX in File Explorer and rename fsx.cfg to fsx.cfg.old. A side-by-side Steam installation may use an FSX-SE folder instead. Restart FSX so it creates a clean configuration, and do not copy old tweaks back until Free Flight works.

   The active configuration is in the Windows user profile, not the main FSX installation directory. Editing the wrong copy is a mistake we see constantly.

4. Remove the custom start-up flight from the test. A saved .FLT file can refer to an aircraft, airport, weather file or add-on that no longer exists. A fresh fsx.cfg normally clears that selection; if necessary, move the suspect .FLT file and its matching .WX file out of the current Documents folder's Flight Simulator X Files directory.

   Also rename Logbook.BIN to Logbook.BIN.old for one test. FSX creates a new logbook automatically, while the renamed file preserves the original.

5. Disable start-up add-ons separately. Rebuilding fsx.cfg does not disable modules listed in dll.xml or programs listed in exe.xml. In the same AppData configuration folder, rename either file with an .old suffix and test again. If that fixes the crash, restore the file and reintroduce its add-on entries individually while keeping the XML well formed.

6. Check the Windows faulting module. Open Event Viewer, look under Windows Logs and Application, and find the error for fsx.exe. A named gauge or add-on DLL points towards that component. If UIAutomationCore.dll appears and FSX closes while opening Free Flight or using menus, follow our dedicated UIAutomationCore menu-fault procedure rather than downloading an arbitrary DLL.

   Generic entries such as ntdll.dll or KERNELBASE.dll often show where the failure surfaced, not which aircraft or add-on caused it.

7. Repair core FSX files last. Steam Edition users can verify the installed files through Steam; boxed-edition users can use the repair facility supplied with their installation media. Verification does not reset damaged AppData settings or saved flights, which is why it comes after the isolation steps. Never mix boxed-edition DLLs with Steam Edition files.

Why does only one aircraft or airport crash FSX?

A crash tied to one selection almost always belongs to that aircraft, airport or an add-on it requires rather than to Free Flight itself.

• One aircraft fails: suspect its panel, compiled gauges, model or an external module. Confirm that another stock aircraft loads at the same airport.
• One airport fails: suspect local scenery, a duplicate airport file or a missing scenery-object library. Load the stock aircraft elsewhere, then disable the newest scenery affecting that region.
• Only one aircraft-and-airport combination fails: the two products may individually work but exceed FSX's available address space together. Traffic and detailed weather can push the same combination over the limit.
• Every stock combination fails: return to the global configuration, start-up modules and core-file checks rather than reinstalling individual aircraft.

When several add-ons are possible, disable half and retest, then repeat with the failing half. This binary approach finds the culprit much faster than removing one item at random.

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

Yes—memory is likely when simple stock flights work but detailed aircraft, airports, weather or high traffic cause a silent close during loading. FSX remains a 32-bit application even on 64-bit Windows, so installed system RAM does not remove its per-process address-space limit.

Test the same route with a stock aircraft, lower traffic and default scenery. If that works, reduce the heaviest components rather than repeatedly rebuilding the configuration; our method for reducing FSX's 32-bit memory use covers the relevant settings and isolation order.

Should I reinstall FSX?

Usually not, because reinstalling often leaves the corrupt user configuration, saved flight and add-on files untouched. A clean fsx.cfg, stock-aircraft test and temporary removal of dll.xml and exe.xml provide a quicker diagnosis.

Use repair or reinstallation only when stock content still fails with clean user settings and no third-party modules. Preserve add-ons first, keep boxed and Steam Edition files separate, and test the base simulator before restoring any aircraft or scenery.