Replace a default aircraft in FS2004 safely: back up stock files, install the correct package, preserve aliases and fix common FS9 errors.
In FS2004 (FS9), replace a default aircraft safely by backing up its entire folder, then installing a complete FS2004 replacement package exactly as its readme specifies. Do not overwrite stock files unless the package is explicitly designed as a drop-in replacement; most downloads should be installed beside the default aircraft and selected instead.
What kind of FS2004 replacement do you have?
The correct installation method depends on whether the download replaces the whole aircraft, its textures, or only one component.
| What you want to change | Correct method |
|---|---|
| Complete aircraft and flight model | Install it as a separate aircraft unless its documentation explicitly requires replacing stock files. |
| Paint scheme only | Add the texture folder and the supplied [fltsim.x] entry. Follow our FS2004 repaint installation procedure. |
| Instrument panel or cockpit | Replace or reference the panel components without disturbing the model. Use our steps for fitting a replacement cockpit panel. |
| Aircraft used by computer-controlled traffic | Treat it as an AI conversion rather than a normal flyable-aircraft replacement. |
A repaint is not a complete aircraft. Likewise, a package containing only a panel, textures or an aircraft.cfg file cannot replace the default model by itself.
How do I replace the aircraft safely?
- Confirm that the package is for FS2004. An FSX-native model may not work in FS9, even if its folders resemble an FS2004 aircraft. Check that the download is a complete aircraft or explicitly identifies itself as a replacement for the named default aircraft.
- Close FS2004. Do not change aircraft files while the simulator is running.
- Back up the original aircraft. Open
[FS2004 installation folder]\Aircraft, copy the default aircraft's complete folder, and store that copy outside the activeAircraftdirectory. Keeping the backup inside that directory can create duplicate menu entries or duplicate configuration titles. - Inspect the downloaded folder structure. A complete aircraft normally has
aircraft.cfgand an.airfile at its top level, together with model, panel, sound and texture folders. Avoid the common nested-folder error:Aircraft\NewAircraft\aircraft.cfgis correct, whileAircraft\NewAircraft\NewAircraft\aircraft.cfgis not. - Install it using the method specified by its author. Put a stand-alone package in its own folder under
Aircraft. Only merge files into the stock folder when the package specifically describes itself as a drop-in replacement. Our complete FS2004 add-on installation checks cover packages that also supply gauges, effects, panels or sounds. - Check for dependencies before removing anything. Open the replacement's
panel.cfgandsound.cfg. Analias=entry may point back to the default aircraft, which means the original folder must remain installed. - Start FS2004 and test the replacement. Check its exterior model, 2D panel, virtual cockpit, sounds, lights, animations and engine start. Do this before deleting or moving any other files.
Should I delete the original default aircraft?
No, leaving the original installed is usually the safer choice. Other add-ons may borrow its panel or sound files, while saved flights and default AI traffic may refer to its internal title= value.
If you want only the replacement shown in the aircraft-selection menu, first verify that it has no dependency on the stock folder. Move the original folder outside FS2004 rather than deleting it permanently. Do not leave two active aircraft with the same title= value because FS9 may load the wrong one or reject one of them.
Why does the replacement aircraft not appear in FS2004?
A missing replacement usually means FS9 cannot find or parse its configuration files.
- Wrong folder depth:
aircraft.cfgis buried inside an extra folder. - Incomplete download: the package is a repaint or update requiring a separate base aircraft.
- Duplicate title: another active
[fltsim.x]section already uses the sametitle=value. - Broken flight-model reference: the
sim=value does not match the name of the supplied.airfile without its extension. - Incorrect component reference: the
model=,panel=,sound=ortexture=entry points to a folder variant that is absent. - Wrong simulator format: the package uses a model or gauge format unsupported by FS2004.
Will saved flights and AI traffic use the new aircraft?
Not automatically. Installing a new aircraft beside the default one gives FS2004 another selectable aircraft, but it does not redirect saved flights or traffic assignments.
Those references may depend on the exact title= identifier in aircraft.cfg. A purpose-built replacement may preserve that identifier, but the old and new versions must not remain active with identical titles. If the actual goal is to update computer-controlled traffic, use the separate method for replacing FS2004 AI aircraft models instead.