Where is aircraft.cfg in FSX, and how do I edit it safely?

In FSX and FSX: Steam Edition, each installed aircraft normally has an aircraft.cfg file in its own folder under SimObjects\Airplanes; helicopters usually sit under SimObjects\Rotorcraft. Close FSX, back up the file, edit it with a plain-text Windows editor, preserve the .cfg extension, then restart FSX and test one change at a time.

Where is the aircraft.cfg file located in FSX?

The file sits inside the individual aircraft's package folder, not in one central aircraft.cfg location.

These are common paths, not guaranteed ones. FSX may be installed on another drive, outside Program Files or in a custom Steam library. Service packs and Acceleration do not create a separate aircraft folder.

How do I find the correct aircraft folder?

Start from the folder containing fsx.exe, then open SimObjects\Airplanes or SimObjects\Rotorcraft. Steam also provides an option to browse the installed game files, which takes you to the correct FSX root folder.

The folder name may not match the name shown in the aircraft-selection menu. Open its aircraft.cfg and inspect the first [fltsim.0] section; entries such as title=, ui_manufacturer=, ui_type= and ui_variation= help identify the package.

A mistake we see constantly is editing a copy still inside an extracted download, a backup folder or a second FSX installation. Check the file's full path before changing it. If an add-on is absent from the standard folders, its location may be declared by a SimObjectPaths.n entry in FSX.cfg.

Is aircraft.cfg the same file as FSX.cfg?

No. aircraft.cfg controls one aircraft package, while FSX.cfg contains simulator-wide settings and SimObject search paths.

The global file is usually under %APPDATA%\Microsoft\FSX; some Steam or side-by-side installations use an FSX-SE folder instead. Our guide to finding the active FSX.cfg and editing it safely explains how to distinguish those installations.

Do I need a flight editor to fix aircraft.cfg?

No; aircraft.cfg is a plain-text configuration file, not a saved flight, so a special flight editor is neither required nor appropriate. A saved FSX flight normally uses a .FLT file in the user's Flight Simulator X Files folder under Documents.

If the saved flight itself is corrupt, changing aircraft.cfg is usually the wrong fix. Edit this CFG file only when repairing or changing the aircraft package.

How do I edit aircraft.cfg safely?

The safe method is to preserve an untouched original, edit a working copy and replace only the intended file.

1. Close FSX completely. This ensures that the simulator reloads the configuration and cannot retain an old value while you test.
2. Show filename extensions. In File Explorer, enable the display of extensions so you can distinguish aircraft.cfg from aircraft.cfg.txt.
3. Confirm the installed file. Check that its path leads through the active FSX installation and the intended aircraft folder, rather than an archive or backup.
4. Make an untouched backup. Copy the original into a separate backup folder. Do not use that copy as your working file.
5. Edit with a plain-text editor. Notepad is sufficient. Avoid Word and other document editors that can introduce formatting, and preserve the existing text encoding where the editor offers that choice.
6. Change one item at a time. Keep section headings, square brackets, equals signs and decimal points intact. Do not rename keys or add units unless the relevant entry specifically expects them.
7. Save the exact filename. The active file must be named aircraft.cfg. If Save As offers a file-type choice, select the all-files option to prevent an added .txt extension.
8. Replace and verify the installed copy. When FSX is under Program Files, copy the edited file back and approve the Windows replacement prompt after checking the destination.
9. Restart FSX and test. Select the affected aircraft and check its menu entry, exterior model, textures, cockpit and flight behaviour. Restore the backup immediately if anything unexpected occurs.

Which Windows editor should I use to fix aircraft.cfg?

Use Notepad or another genuine plain-text editor. An editor with line numbers can make troubleshooting easier, but syntax highlighting and specialist aircraft-editing software are not required.

A CFG file is still text even when Windows labels it as a “CFG File” or displays it simply as aircraft. The latter means known filename extensions are hidden.

Which aircraft.cfg entries most often break an aircraft?

Most broken aircraft and repaint installations trace back to a small group of references in the [fltsim.x] sections.

• [fltsim.x] numbering should begin at [fltsim.0] and continue without duplicate numbers or gaps.
• Every title= value must be unique among the aircraft loaded by FSX. Copying an existing block without changing its title can prevent a variation from loading correctly.
• texture=blue points to a folder named texture.blue. An empty texture= normally points to the unsuffixed texture folder.
• model=winglets points to model.winglets. An empty model= can be intentional and normally uses the plain model folder.
• sim= must match the base name of the corresponding .air file, without its extension.
• Blank panel= and sound= values can also be deliberate. Do not fill them merely because they appear empty.

For repaint and variation work, see our explanation of how FSX reads and numbers [fltsim.x] entries before copying a block from another package.

Why can't I save aircraft.cfg in Windows?

Windows often blocks direct saving because the FSX installation is inside a protected Program Files directory. Copy the file to the Desktop or another writable folder, edit it there, then copy it back and accept the administrative replacement prompt.

Do not disable User Account Control or weaken permissions across the whole FSX directory for one edit. If access is still denied, the filename changes to .txt, or Windows redirects the saved copy, follow our safe fixes for aircraft.cfg save and permission problems.

Why are my aircraft.cfg changes not taking effect?

An ignored edit usually means FSX is reading another copy, the file was saved with the wrong extension, or the simulator has not reloaded the aircraft configuration.

If the installed file contains the change but FSX still ignores it, use our checklist for diagnosing aircraft.cfg changes that do not take effect.

What should I do if the aircraft disappears after editing?

Restore the backup first; a complete disappearance usually indicates invalid syntax or a broken variation entry rather than a texture problem. Once the aircraft returns, repeat only the required edit and test before changing anything else.

Without a backup, restore an add-on from its original archive or reinstall it. Steam's file-verification function can recover modified default FSX files, but it may also replace other customised default files, so use it as a recovery measure rather than the first fix.