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

In FSX and FSX: Steam Edition, each aircraft has its own aircraft.cfg inside its folder under SimObjects\Airplanes; helicopters are usually under SimObjects\Rotorcraft. Close FSX, back up the original file, edit it in a plain-text editor, preserve the exact filename, and test one change at a time.

Where is the aircraft.cfg file located?

The usual location depends on your FSX edition and installation folder:

These are common defaults, not guaranteed locations. FSX may be installed under Program Files, on another drive or in a custom Steam library. Open the folder containing fsx.exe, then follow SimObjects\Airplanes into the folder for the aircraft you want to change.

Each aircraft folder normally contains one aircraft.cfg, which may define several selectable variants through its [fltsim.x] sections. If Windows hides known file extensions, the file may appear simply as aircraft with a type such as CFG File.

Some add-ons use an additional SimObjects location configured through SimObjectPaths.n entries in the global FSX configuration. If the aircraft is not in either standard SimObjects folder, check the paths in [Main] using our instructions for finding and safely inspecting the simulator-wide FSX.cfg.

Is aircraft.cfg the same as FSX.cfg?

aircraft.cfg controls one aircraft package, while FSX.cfg stores simulator-wide settings such as graphics, controls and SimObject search paths. Editing one does not edit the other.

How do I edit aircraft.cfg safely?

1. Close FSX completely. Do not edit the active file while the simulator is running, because FSX may retain old values or overwrite unexpected changes.
2. Show filename extensions. Enable file extensions in Windows File Explorer so that you can distinguish aircraft.cfg from an accidental aircraft.cfg.txt.
3. Make a backup. Copy the untouched file somewhere safe or create a copy named aircraft.cfg.original. Keep that backup until the aircraft has loaded and flown correctly.
4. Use a plain-text editor. Notepad is sufficient. Do not use Word or another editor that can insert document formatting, and leave the file's text encoding unchanged if your editor offers that choice.
5. Change only the required line. Preserve section names, square brackets, equals signs and existing units. Make one logical change at a time so that a bad value is easy to identify.
6. Save the exact filename. The active file must remain aircraft.cfg. If using Save As, select an all-files option rather than allowing the editor to append .txt.
7. Test the affected aircraft. Restart FSX, select the aircraft and check both its appearance and operation. Reopen the installed file afterwards if you need to confirm that Windows saved the change in the intended folder.

Which aircraft.cfg entries commonly cause problems?

The most frequent failures come from repaint entries and references to files or folders that do not exist:

• [fltsim.x] numbers should be unique and consecutive. Use the next number after the highest existing entry rather than duplicating an index or leaving a gap.
• Each title= value must be unique. A duplicate title can cause FSX to reject or skip a variation.
• texture=blue refers to a folder named texture.blue, while an empty value normally refers to the plain texture folder.
• model=winglets refers to model.winglets. Blank model=, panel= or sound= values can be intentional, so do not fill them without checking the folder layout.
• sim= must match the base filename of the aircraft's corresponding .air file, without the extension.

When adding a repaint, follow the complete aircraft.cfg and texture-folder procedure for FSX liveries rather than copying a [fltsim.x] block without checking its references.

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

Windows may block direct edits because FSX is installed under a protected Program Files directory. The safest approach is to copy aircraft.cfg to the Desktop, edit it there, and copy it back into the aircraft folder, accepting the administrative replacement prompt.

Do not disable User Account Control or loosen permissions across the entire FSX installation just to change one file. If the replacement is still denied, follow our aircraft.cfg permission and save-error fixes, then verify that the file inside the real FSX folder contains your edit.

Why did the aircraft disappear after editing aircraft.cfg?

An aircraft that vanishes from the selection menu usually has a malformed or duplicate [fltsim.x] entry, an invalid title=, or a broken sim= reference. An aircraft that appears but has missing geometry or textures more often has an incorrect model= or texture= value.

Restore the backup first. If that returns the aircraft, reapply the intended change one line at a time and compare folder suffixes exactly. Our diagnostic checklist for invisible or incomplete add-on aircraft covers the associated model, texture and folder-layout faults.

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