Diagnose white lines on FS2004 airport surfaces: identify texture seams, duplicate AFCADs, z-fighting, normal markings and scenery conflicts.
White lines on FS2004 (FS9) airport surfaces are usually normal painted markings, seams in damaged or mismatched surface textures, or z-fighting from overlapping scenery. Fixed lines that repeat in a grid point to textures; lines that flicker as the camera moves usually mean two runway, apron or taxiway surfaces are being drawn together.
What causes white lines on FS2004 airport surfaces?
The line’s position, pattern and behaviour usually reveal which part of FS2004 is at fault.
| What you see | Likely cause | Best first check |
|---|---|---|
| Straight lines following runway edges, centrelines or thresholds | Normal airport markings | Compare their position with the airport layout |
| Thin fixed seams forming a regular grid | Damaged textures, mismatched texture sets or defective mipmaps | Test several unmodified default airports |
| Lines that flicker, shimmer or swap colour as the view moves | Z-fighting between overlapping surfaces | Check for duplicate airport-definition BGLs and competing scenery layers |
| Lines confined to one add-on airport | A local scenery conflict, custom ground polygon or missing package texture | Disable that airport’s Scenery Library entry |
| Bright strips around the airport perimeter | Overlapping ground polygons, flattens, exclusions or elevation conflicts | Disable other scenery covering the same area |
How do I remove the white surface lines?
The safest fix is to identify whether the fault follows one airport, every airport or a particular viewing condition before replacing any files.
- Rule out intentional markings. View the airport from above in daylight. Runway centrelines, edges and threshold bars are normally white; taxiway centrelines and most taxiway edge markings are yellow. White apron, stand and parking guidance lines may also be intentional in custom scenery.
- Test the scope of the problem. Compare the affected airport with an unmodified default airport outside the add-on’s coverage area. A defect at one airport points to local scenery. Identical seams at many airports point towards shared surface textures, graphics settings or a global replacement package.
- Disable the suspect scenery layer. Record its position in the Scenery Library, untick it, close FS2004 completely and restart. If the lines disappear, another active airport file or surface in that package is responsible. Remember that disabling a scenery layer does not restore textures previously copied into a shared FS2004 texture folder.
- Remove duplicate airport files from the test. Look through active scenery folders, including
Addon Scenery\scenery, for older AFCADs, alternative airport layouts and files installed by AI-traffic packages. File names often include the ICAO code, but many do not. Move one candidate at a time outside every active scenery folder rather than deleting it; our method for isolating duplicate airport-definition files covers the common hiding places and priority problems. - Restore one complete texture set. If the lines began after a texture installation, restore the package’s original backup or a clean matching set. Do not combine selected bitmaps from several airport-environment packages: their edge padding, alpha channels and mipmaps may not match. Use our guidance on troubleshooting overwritten or mixed FS2004 textures before copying more files into shared folders.
- Reset graphics overrides for comparison. Where available, return the graphics-driver profile to application-controlled settings. Test FS2004’s filtering, anti-aliasing and mipmapping options one at a time, restarting and returning to the same saved viewpoint after each change. Anti-aliasing may change how an edge looks, but it cannot remove a second overlapping surface.
- Repair default files only after isolating the fault. Consider an installation repair only if the lines remain at several default airports with add-on scenery disabled and driver overrides reset. Preserve the existing installation and add-on folders first; blindly reinstalling over a modified FS2004 setup can overwrite working files without removing the conflicting ones.
A mistake we see often is installing another airport texture pack before proving that textures are responsible. That may disguise a bad seam, but it cannot cure z-fighting and can make recovery harder by replacing shared files.
Why do the white lines flicker when the view moves?
White lines that flicker with camera movement usually indicate z-fighting: FS2004 is trying to draw two surfaces at the same, or almost the same, height.
Typical sources include an add-on airport running alongside an older AFCAD, an airport BGL supplied with an AI-traffic package, two versions of the same scenery, or a custom apron placed over another ground polygon. Scenery priority alone does not guarantee that the lower surface disappears; the add-on also needs appropriate exclusions or compatible geometry.
Disable one candidate at a time and restart FS2004 after each change. Do not remove stock scenery merely because an add-on covers the same airport. For a closer diagnosis, follow our checks for separating texture shimmer from overlapping scenery.
An elevation or flatten conflict more often produces a step, embankment, trench or broad bright strip than a fine tiled line. That distinction helps avoid editing airport elevations when the real problem is a texture seam.
Are white runway and taxiway lines normal?
Some white lines are correct airport markings and should not be removed.
- Runway centrelines, edge lines, threshold markings and aiming-point markings are normally white.
- Taxiway centrelines, edge markings and runway holding-position markings are generally yellow.
- Aprons may contain white stand outlines, lead-in lines or locally styled markings, particularly in add-on scenery.
A rendering fault is more likely when the line cuts across unrelated surfaces, outlines every texture tile, appears where two scenery packages meet, or changes rapidly with distance and viewpoint.
Why do the lines appear only at night, in one season or at certain distances?
Lines limited to one lighting, seasonal or distance condition usually come from a particular texture variant or mipmap level rather than the airport layout itself.
- Only at night: suspect a defective night texture, alpha channel, lighting polygon or incomplete add-on texture set.
- Only in one season: check seasonal terrain textures around the airport and whether the scenery package supplied a complete matching set.
- Only at a particular distance: suspect malformed mipmaps or edge pixels bleeding into the next texture tile.
Restore the whole matching texture package rather than replacing only the variant that looks wrong. A partial replacement can move the seam to another season, time of day or viewing distance.
Should I edit the AFCAD or replace the textures?
Edit the airport layout only when the defect follows incorrect runway, taxiway or apron geometry and duplicate files have already been ruled out.
In FS2004 discussions, “AFCAD” often means any airport facility BGL, not just a file made with the original AFCAD editor. Such a file can define runways, taxiways, aprons, parking and navigation data, but it cannot repair a damaged bitmap or directly alter every custom ground polygon compiled into a scenery BGL.
- Choose an AFCAD edit when one active airport file has the wrong layout or an apron has been drawn over another airport surface.
- Choose texture restoration when fixed seams repeat across tiles or appear at several unrelated airports.
- Remove a conflict instead when the lines flicker and two airport-definition files are active.
If the airport geometry genuinely needs correction, use a copy of the add-on file and follow the procedure for editing an FS2004 airport layout without damaging the original. Keep edited files in their own scenery layer so they can be disabled or replaced without touching the stock installation.