Fix “airplanes must have unique titles” in FSX and Steam Edition by finding duplicate title= entries, removing clones or renaming a valid repaint.
FSX and FSX: Steam Edition show “airplanes must have unique titles” when two loaded [fltsim.x] sections contain the same title= value. Close the simulator, back up the relevant aircraft.cfg files, then remove the accidental duplicate or change one legitimate repaint to a unique title. Renumbering [fltsim.x] alone does not solve it.
What does the unique aircraft titles warning mean?
title= is FSX’s internal identifier for an aircraft variation, and it must be unique across every active aircraft.cfg the simulator loads. It is not limited to the other liveries in the same aircraft folder. Boxed FSX and FSX: Steam Edition apply the same rule.
The conflict usually appears after one of these changes:
- A repaint’s
[fltsim.x]block was copied without changing itstitle=value. - An entire aircraft folder was copied or backed up inside an active
SimObjectspath. - The same add-on exists in two paths loaded by FSX.
- An installer added a livery that was already present.
- Two unrelated add-ons happen to use the same generic title.
The section number, folder name and menu label are separate from the internal title. Our explanation of how FSX reads each [fltsim.x] entry covers those relationships in more detail.
How do I find and fix the duplicate title= entries?
Find every occurrence of the reported title, decide which entries are genuine, and leave that exact value in only one active section.
- Close FSX and make an external backup. Copy the affected
aircraft.cfgfiles somewhere outside everySimObjectsfolder. A backup left beside the aircraft as a copied aircraft folder may itself be scanned and create another duplicate. - Record the conflicting title. If the warning supplies a title, copy it exactly. If it does not, begin with the aircraft, repaint or installer used immediately before the warning appeared.
- Locate the active aircraft files. The normal relative location is
SimObjects\Airplanesbeneath the FSX installation, but the full boxed and Steam paths depend on where each edition was installed. Use our guide to locating and safely editing the correctaircraft.cfgif there is any doubt. - Check every loaded path. Extra locations can be listed as
SimObjectPaths.Nentries under[Main]in the activefsx.cfg. If you use both boxed and Steam editions, make sure you are inspecting the installation that produced the warning. From a Command Prompt opened at a loadedSimObjectsfolder,findstr /s /i /n /c:"Exact Reported Title" *.cfgcan locate matching text recursively. - Choose the appropriate repair. Remove a redundant aircraft folder or repeated livery block. If both entries are valid liveries you want to retain, give one a descriptive title such as
title=C172 Blue G-ABCD. Do not rely on capitalisation or an invisible trailing space to make it different. - Clean up the remaining sections. When deleting a repeated repaint, remove its complete
[fltsim.x]block rather than just itstitle=line. Renumber the surviving blocks consecutively from[fltsim.0]; gaps can prevent later variations from appearing even though numbering was not the original cause. - Save and restart FSX. Confirm that the file is still plain text named
aircraft.cfg, notaircraft.cfg.txt. FSX can reveal conflicts one at a time, so another warning may identify a separate duplicated title.
To test a whole aircraft folder without deleting it, move the folder outside every configured SimObjects path and restart FSX. Merely renaming the folder while leaving it under SimObjects\Airplanes does not reliably stop FSX from scanning it.
I want it to be clean: should I delete or rename the duplicate?
Delete accidental copies; rename a title only when both entries represent aircraft variations you genuinely intend to keep.
| Situation | Clean repair |
|---|---|
| Two identical aircraft folders | Move one outside SimObjects, test the remaining copy, then remove the redundant folder. |
The same [fltsim.x] block appears twice | Delete the complete repeated block and renumber the remaining sections. |
| Two different, valid liveries share a title | Give the newer or user-aircraft livery a descriptive unique title=. |
| You cannot tell which copy is needed | Quarantine the suspected folder outside FSX first; do not permanently delete it until the aircraft, panels and liveries have been checked. |
If adding a repaint caused the warning, compare the entry with the correct FSX livery installation structure. Renaming a genuinely duplicated repaint may suppress the warning while leaving two identical menu entries, so removal is cleaner in that case.
Which aircraft.cfg value fixes the warning?
Only a duplicated title= value causes this warning; changing display labels, texture references or section numbers will not make the internal identifier unique.
| Entry | What it controls | Will changing it fix the warning? |
|---|---|---|
title= | The internal identifier used for that aircraft variation | Yes, if the replacement is genuinely unique |
ui_variation= | The livery name displayed in the aircraft menu | No |
[fltsim.x] | The block’s sequence within one configuration file | No, although the sequence should remain consecutive |
texture= | The suffix of the repaint’s texture folder | No; an incorrect value can produce missing or white textures |
sim= | The base name of the flight-dynamics file | No; changing it can stop the aircraft loading |
| Aircraft folder name | The folder containing the add-on | No |
I changed title= and still nothing changed
If you saved the edit and still nothing changed, FSX did not read that file or another copy of the title remains active.
- FSX was not restarted: aircraft configuration changes are not reliably reloaded while the simulator is running.
- The wrong installation was edited: this is common on systems containing both boxed FSX and FSX: Steam Edition.
- The edit was not saved: reopen the same file and verify the new line. Windows may require administrator approval when replacing a file beneath a protected installation folder.
- The filename changed: enable file extensions in Windows and check for
aircraft.cfg.txt. - A second copy remains: search all configured
SimObjectPaths.Nlocations, not just the standardAirplanesfolder. - There are several conflicts: fixing one pair may allow FSX to report the next duplicated title.
Our checks for an aircraft.cfg edit that FSX appears to ignore cover incorrect files, save permissions and restart issues.
Can changing the title break AI traffic or saved flights?
Yes. AI traffic files, missions and saved flights may refer to an aircraft by its exact title= value.
For an AI aircraft, preserve the title expected by the traffic package and remove or rename the accidental clone instead. If the conflict is between an AI model and an ordinary user repaint, changing the user repaint is normally safer. A renamed aircraft may also stop an existing saved flight from resolving the variation it originally used.
What if the aircraft disappears after the fix?
A missing aircraft usually means its [fltsim.x] sequence or one of its file references was damaged while the duplicate was removed.
Check that the first variation begins with [fltsim.0], later sections are numbered consecutively, and each remaining block still has a title= line. Also verify that sim=, model=, panel=, sound= and texture= still refer to the intended files or folder suffixes. Restore the backup and repeat the edit if more than the duplicated block was removed.
Does “Unreal Engine stuck at 0 seconds remaining” have anything to do with this?
No. FSX and FSX: Steam Edition do not use Unreal Engine, and an installer or launcher stuck at 0 seconds remaining is unrelated to the “airplanes must have unique titles” warning.
Do not edit aircraft.cfg to repair a stalled progress timer. If a separate installer remains at zero with no disk or network activity, close it, restart Windows, confirm that sufficient storage is available and retry the installation. Apply the duplicate-title repair only if FSX itself subsequently reports the unique-titles warning.