FSX smoke and contrails show as black squares when transparency fails. Fix FX_1.bmp, test DirectX 10 Preview and repair add-on effects.
Smoke and contrails appear as black squares in FSX when the particle texture’s transparency is missing, corrupt or rendered incorrectly. The usual culprit is FX_1.bmp in Effects\texture; legacy add-on effects under DirectX 10 Preview can cause the same symptom. Restore the texture first, then test FSX without DX10 Preview.
What causes black square smoke in FSX?
The squares are the normally invisible edges of FSX’s rectangular particle sprites, exposed because their alpha transparency has failed. Smoke, contrails and dust are drawn from small images whose alpha channel makes the area surrounding each particle transparent.
Several effects can share FX_1.bmp, so one damaged or incorrectly converted file may break particles across multiple aircraft. Opening and resaving this texture in an ordinary image editor can strip its alpha channel while leaving the visible image apparently intact.
| Symptom | Likely cause | Best next step |
|---|---|---|
| Stock and add-on smoke, contrails or dust all show squares | Damaged shared FX_1.bmp | Restore the texture in Effects\texture |
| Only one aircraft or effect is affected | Missing or incompatible custom texture | Reinstall that add-on’s Effects files |
| Squares appear only with DirectX 10 Preview enabled | Legacy effect is incompatible with the preview renderer | Disable DirectX 10 Preview and restart FSX |
| The entire simulator view is black | Display, driver or configuration fault rather than a particle texture | Use our separate FSX black-screen troubleshooting steps |
How do I replace FX_1.bmp safely?
Replacing the shared texture in the active FSX installation is the quickest reliable fix when several particle effects are affected.
- Close FSX completely. The simulator should not be running while its effect files are changed.
- Locate the active FSX folder. Boxed installations commonly use a folder ending in
Microsoft Flight Simulator X; Steam installations normally end inSteam\steamapps\common\FSX. Use the installation actually launched by your shortcut if both editions are present. - Back up the existing texture. Copy
Effects\texture\FX_1.bmpsomewhere outside the FSX directory before replacing it. - Obtain a clean copy. Our known-good replacement smoke texture supplies the required
FX_1.bmp. - Copy it into the correct directory. Place the file in
FSX\Effects\textureand approve replacement when prompted. Do not put it in the root-levelTexturefolder or an aircraft’s texture folder. - Restart and test a stock effect. Confirm that a default smoke or contrail effect renders correctly before testing third-party aircraft.
If Windows does not ask whether to replace the existing file, check that you have found the active installation and that file extensions are visible. A file accidentally named FX_1.bmp.bmp will not be loaded. Installation under a protected Windows folder may also require administrator approval for the copy.
What if the black squares remain?
Persistent squares usually point to DirectX 10 Preview, a separate custom effect texture or the wrong FSX installation being repaired.
Does DirectX 10 Preview cause black smoke squares?
DirectX 10 Preview is the likely cause if the same effect works normally with that option disabled. Clear Preview DirectX 10 in FSX’s display or graphics settings, close the simulator and launch it again; changing the option without restarting may not provide a valid test.
If disabling it fixes the particles, stay with the standard renderer or use an effect specifically prepared for the preview renderer. Anti-aliasing and general quality sliders will not restore a missing alpha channel.
Why does it happen on only one aircraft?
A single affected aircraft normally uses a custom particle texture rather than the shared FX_1.bmp. Its effect definition may be present while the matching texture was omitted, installed in the wrong folder or saved in an unsupported format.
Reinstall the aircraft’s supplied Effects and Effects\texture files while preserving their folder structure. If it came from our library, retrieve the original package from the FSX aircraft and add-on downloads section rather than mixing effect files from an unrelated aircraft.
Will Steam file verification repair the texture?
Steam’s file verification can restore a damaged stock FX_1.bmp, but it may also replace other modified stock files. Back up customised content first. Verification cannot restore a third-party texture that was never included with FSX: Steam Edition; that file must come from the affected add-on package.
For boxed FSX, restore the texture from a known-good backup or installation source. Avoid resaving it in a general-purpose image editor, since losing the alpha channel recreates the black-square fault.