Turn off mid-air collision detection in FSX while keeping terrain crashes enabled, plus fix multiplayer or configuration overrides.
To turn off mid-air collision detection in FSX or FSX: Steam Edition, open Settings, choose Realism, clear Allow collisions with other aircraft, and select OK. Leave Detect crashes and damage enabled if you still want ground, terrain and overstress crashes.
How do I disable only aircraft-to-aircraft collisions?
Clearing the aircraft-collision option stops FSX treating contact with AI or multiplayer aircraft as a crash without disabling the rest of its damage system.
- Open Settings from the main FSX screen.
- Select Realism.
- Under Crashes and damage, clear Allow collisions with other aircraft.
- Keep Detect crashes and damage selected if runway, terrain and scenery impacts should still end the flight.
- Select OK to save the setting.
| Realism setting | Other aircraft | Ground and scenery |
|---|---|---|
| Allow collisions cleared | No collision crash | Crash detection remains active |
| Ignore crashes and damage selected | No collision crash | Crash detection is disabled |
| Allow collisions enabled | Contact can cause a crash | Crash detection remains active |
What changes when aircraft collisions are disabled?
AI and multiplayer aircraft can pass through your aircraft without FSX resetting or ending the flight. The setting does not remove traffic, hide other aircraft or alter their routes; it changes only the collision response.
A mistake we see frequently is selecting Ignore crashes and damage when only mid-air collisions are unwanted. That broader option also prevents normal crash detection after hitting terrain, buildings or the runway.
Can multiplayer session rules override the setting?
In FSX multiplayer, the host's session rules can control aircraft collisions and may override or lock a participant's local choice. If the option is unavailable or collisions continue, the host should disable aircraft collisions in the session settings.
Boxed FSX and Steam Edition use different networking arrangements, so our explanation of how FSX multiplayer works online and offline is useful when the problem occurs only in a shared session.
Why does the collision setting keep turning itself back on?
FSX may fail to retain the option when its active configuration file is read-only, Windows prevents the file from being updated, or the wrong FSX profile is being edited.
- Save through the menu first: Change the Realism setting, select OK, close FSX normally and reopen it to check that the choice persisted.
- Check the active configuration: Steam installations can use an FSX or FSX-SE profile name depending on whether boxed FSX has also existed on that Windows account.
- Remove read-only status: Back up the active configuration file before changing its properties or contents.
- Check aircraft-specific systems: Some add-on aircraft implement their own failure or damage logic, which FSX's global collision option may not control.
If the menu cannot save the option, close FSX and edit the active simulator configuration file. Under [REALISM], set CrashWithDyn=False. Keep CrashDetection=True if terrain and scenery crashes should remain enabled. Do not edit the file while FSX is running, because the simulator may overwrite the change when it closes.
If several preferences are being reset rather than this setting alone, our FSX settings and troubleshooting library covers the related configuration symptoms.