Why does my aircraft sink into the runway in FSX?

In FSX and FSX: Steam Edition, an aircraft sinks into the runway because its landing-gear contact points do not match the visual model, or because the airport's visible surface and collision elevation disagree. Test another aircraft and airport first; that identifies whether the aircraft configuration or scenery needs repair.

Is the aircraft or airport causing the sinking?

A two-way cross-test usually separates an aircraft fault from a scenery fault.

1. Start a new Free Flight with a default aircraft at the affected airport.
2. Move the problem aircraft to a stock airport where no add-on scenery is active.
3. Compare the results. Do not edit the aircraft if several aircraft fail only at one airport, and do not alter airport elevation if only one aircraft fails everywhere.

How do I fix incorrect FSX landing-gear contact points?

Edit the aircraft configuration only when the fault follows that aircraft to other airports.

1. Close FSX and make a backup. Copy the aircraft's complete folder or at least its aircraft.cfg file. If necessary, follow our instructions for finding the FSX aircraft installation folder.
2. Open the contact-point section. In aircraft.cfg, find [contact_points]. Wheel entries normally follow the pattern point.n = 1, longitudinal, lateral, vertical, ...; the type value 1 identifies a wheel.
3. Inspect the vertical position. It is the third positional value after the type and is measured in feet relative to the aircraft reference datum. A more negative value places that contact point farther below the aircraft, raising the corresponding part of the visual model relative to the runway.
4. Change one gear position at a time. Use small adjustments, preserve every comma and test after each edit. If all wheels are buried by the same amount, adjust all wheel points consistently; if only the main gear is wrong, do not move the nose or tail wheel unnecessarily.
5. Reload the aircraft in a fresh flight. Switching aircraft may reload the configuration, but restarting FSX gives a cleaner test when results appear unchanged.

A mistake we see constantly is copying contact points from an aircraft that merely looks similar. Contact positions depend on that model's own reference datum and geometry, so borrowed values can produce tipping, bouncing, brake problems or an aircraft suspended above the runway.

The static_cg_height and static_pitch values influence initial placement, but they are not substitutes for correct wheel points. If the aircraft spawns at the right height and then drops as its weight settles onto the gear, inspect the contact points and suspension-compression values. A clean reinstall of the aircraft is safer when the configuration has already been heavily edited.

If the fuselage height is correct and only the visible tyres penetrate the surface, raising the whole aircraft will create a new error. That symptom usually requires corrected wheel geometry, animation or configuration from the aircraft package.

How do I fix an airport where every aircraft sinks?

If every aircraft sinks at one airport, the airport's visible runway and its physical ground surface are at different elevations.

1. Disable the add-on airport temporarily in the FSX Scenery Library, restart the simulator and retest. If the default airport works, the add-on or another package covering the same area is responsible.
2. Check for duplicate airport definitions. Two BGL files defining the same airport can supply conflicting runway elevations, flattens or hardened surfaces. Do not delete files at random or remove default FSX scenery.
3. Correct the scenery priority. A dedicated airport should normally sit above broad regional scenery and terrain packages in the Scenery Library.
4. Check elevation-correction files. Some airport installers place a separate altitude BGL in Scenery\World\Scenery. An old file can remain active after the main airport is removed. Move only a file that you can positively match to the airport, and keep a backup.
5. Reinstall or correct the airport. The airport definition, flatten and visual runway must use compatible elevations. Our airport elevation and duplicate-scenery checks cover this conflict in more detail. Experienced scenery editors can use the Airport Design Editor workflow for FSX to inspect the airport altitude and flatten rather than guessing.

Can terrain mesh make an aircraft sink into a runway?

Terrain mesh can expose or exaggerate an airport elevation mismatch, but it does not repair incorrect aircraft contact points.

Disable the mesh package briefly to confirm its involvement. If that removes the problem, check scenery priority and the airport's elevation data instead of leaving terrain detail permanently reduced; our FSX terrain-mesh configuration guidance explains the relevant ordering and elevation checks.

Why does it happen only in a saved flight?

An old saved flight can retain an aircraft position and altitude that no longer match the airport after scenery has been installed, removed or corrected.

Select the airport again from Free Flight and create a new flight rather than loading the old save. Once the aircraft starts on the runway correctly, replace the saved flight if needed.

What if the aircraft sinks only on touchdown?

Touchdown-only sinking usually points to excessive gear compression, damaged landing gear or a landing that exceeds the aircraft's limits.

Test with a normal touchdown and watch the external view. If the aircraft repeatedly settles below the surface after gentle landings at several airports, return to the contact-point and suspension values. If it begins sinking while still airborne, that is an approach or flight-dynamics problem rather than runway geometry.