Turn off mid-air collision detection in FSX or Steam Edition without disabling terrain crashes, aircraft damage or other realism settings.
To turn off mid-air collision detection in FSX or FSX: Steam Edition, open Settings, select Realism, clear Allow collisions with other aircraft, then select OK. Keep Detect crashes and damage selected if you still want impacts with terrain, runways and scenery to register as crashes.
How to disable only aircraft-to-aircraft collisions
Clearing the aircraft-collision option disables mid-air collision crashes without switching off the rest of FSX's built-in damage detection.
- From the opening screen, select Settings and then Realism. During a flight, reveal the menu bar if necessary and open Options, Settings, then Realism.
- Under Crashes and damage, select Detect crashes and damage.
- Clear Allow collisions with other aircraft.
- Select OK to save the change.
If the aircraft-collision option is greyed out, select Detect crashes and damage first. Choosing Ignore crashes and damage makes the separate collision control unnecessary and may disable it in the menu.
Which FSX realism setting should I choose?
Choose the aircraft-collision checkbox when only contact with AI or multiplayer aircraft should be ignored; choose the broader ignore-damage setting only when no normal crash detection is wanted.
| Realism configuration | Other aircraft | Terrain and scenery |
|---|---|---|
| Detect crashes enabled; aircraft collisions cleared | Contact does not cause an FSX crash | Crash detection remains active |
| Ignore crashes and damage selected | Contact does not cause an FSX crash | Built-in crash detection is disabled |
| Detect crashes and aircraft collisions enabled | Contact can end or reset the flight | Crash detection remains active |
A common mistake is selecting Ignore crashes and damage when only mid-air collisions are unwanted. That broader choice also stops FSX responding normally when the aircraft hits terrain, a building or another scenery object.
What changes after aircraft collisions are disabled?
AI and multiplayer aircraft can overlap or pass through your aircraft without FSX ending or resetting the flight because of that contact.
The option does not hide traffic, alter AI routes or prevent another aircraft from occupying the same space. It changes the collision response only. This is useful in crowded multiplayer sessions and formation flights, where network position updates can otherwise produce an unwanted collision result.
Does this remove AI aircraft?
Disabling collisions leaves AI traffic visible and operating at the selected traffic density.
Keep the traffic and disable collisions when you want a busy airport without collision resets. If your aim is clearer airspace, fewer runway conflicts or lower simulator load, use the separate controls for reducing or disabling FSX AI traffic.
Does it disable aircraft damage and engine failures?
No. Aircraft stress, engine failures and other damage behaviour remain controlled by their own realism or add-on settings.
If you want a broader no-damage configuration, our guide to the separate crash, stress and engine-failure controls explains which options need changing. Some complex add-on aircraft also run independent failure systems that FSX's global collision setting cannot override.
Can multiplayer session rules override the setting?
Yes. An FSX multiplayer host can apply session collision rules that override or restrict a participant's local preference.
If collisions occur only during multiplayer, check the host's session options rather than repeatedly changing your own Realism menu. The host must disable aircraft collisions for that session when the rule is being enforced centrally.
Why does the collision setting keep turning itself back on?
A setting that reverts after restarting FSX usually means the active configuration file was not updated, is read-only or is not the file being inspected.
- Save and close normally: Change the option, select OK, exit FSX normally and reopen it. Ending the simulator through Task Manager can prevent preferences from being written.
- Check the correct profile: Boxed FSX normally uses
%APPDATA%\Microsoft\FSX\FSX.CFG. Steam Edition may use that location or anFSX-SEprofile withFSX_SE.CFG, depending on the installation history of that Windows account. - Check file properties: Back up the active configuration file, then make sure it is not marked read-only and that the Windows account can update it.
- Identify wider configuration trouble: If display, control or traffic settings also revert, use our FSX configuration and settings troubleshooting answers rather than treating this as a collision-only fault.
As a last resort, close FSX and open the active simulator configuration file. Under [REALISM], set CrashWithDyn=False. Leave CrashDetection=True if terrain and scenery crashes should continue to work.
Edit only the active file and make a backup first. FSX can overwrite manual changes if the configuration is edited while the simulator is running.
Why do I still get a crash message?
The aircraft-collision switch does not suppress crashes caused by terrain, airport objects, scenery or an add-on's own damage system.
First confirm what the aircraft contacted. If another model passed through you but the crash occurred beside a building, jetway or uneven scenery surface, FSX may have detected the scenery object instead. If the message comes from an add-on aircraft rather than FSX's standard crash handling, change that aircraft's own failure or damage options.