FSX & FSX: Steam Edition Updated Fri, 10 Jul 2026 23:35:24 GMT 6 min read

How do I create custom AI traffic in FSX?

Create custom AI traffic in FSX with aircraft, schedules and traffic BGLs. Follow the workflow and fix missing traffic, timing and format problems.

By Ian StephensEditor-in-Chief

To create custom AI traffic in Flight Simulator X, install an AI-compatible aircraft, build a timetable between valid airport ICAOs, compile the aircraft, airport and flight-plan data into a traffic .bgl, then place that file in an active scenery folder. Match the aircraft's title= exactly and test at the scheduled UTC time.

What does FSX need for custom AI traffic?

FSX custom AI traffic needs an installed aircraft, valid airport records and a compiled timetable.

Aircraft: The chosen aircraft or repaint must be installed under SimObjects\Airplanes. Its flight-plan entry must match the exact title= value from the relevant [fltsim.x] section of aircraft.cfg.
Airports: Each departure and destination needs a valid ICAO identifier, position and elevation in the compiler's airport data. An airport found only in add-on scenery may need to be added manually.
Flight plans: Each rotation defines the aircraft, registration or flight number, traffic percentage, IFR or VFR operation, cruise level, departure time and destination.

Classic traffic compilers represent this information as separate aircraft, airport and flight-plan lists. Most graphical tools hide the text syntax, but the resulting traffic .bgl contains the same basic relationships. FSX and FSX: Steam Edition use the same system; only their installation locations may differ.

Choosing an FSX AI traffic tool

Choose the tool according to the number of routes you are creating and whether you need to work with an existing BGL.

Workflow	Best for
Visual airline and general-aviation timetable editing	Creating a small number of rotations from aircraft and textures already installed in FSX.
Building, decompiling and recompiling traffic data	Creating source files or recovering editable aircraft and schedule data from your own traffic BGL.
A spreadsheet-based airport, route and timing workflow	Planning larger sets of aircraft, routes, flight levels and departure times in bulk.

Can I edit an existing traffic BGL?

Yes, provided it is your own file or you have permission to modify it. Decompile the traffic BGL, edit the resulting aircraft and flight-plan data, then compile a new BGL. Keep the original as a backup and remove it from active scenery before testing the replacement, or both schedules may run.

A traffic compiler cannot edit airport scenery, aircraft models or an arbitrary scenery BGL. Confirm that the file really is an AI traffic database before trying to decompile it.

How to create and install an AI traffic BGL

The safest method is to prove one simple return route before building an entire airline schedule.

Check the aircraft entry. Open aircraft.cfg and copy the exact title= value for the required livery. Do not substitute ui_type, ui_variation or the texture-folder name. Every installed aircraft title should be unique, and its sim= and model= references must point to valid files and folders.
Select the airports. Start with two stock FSX airports whose ICAOs are recognised by the tool. If using add-on scenery, check that the compiler has the correct airport position and that the airport offers parking large enough for the aircraft.
Build a complete rotation. Add an outbound and return leg, with enough time for the flight and a sensible turnaround. FSX schedules use UTC rather than airport local time. Day numbering and weekly-repeat controls vary between editors, so check the tool's own labels rather than assuming Monday is represented by a particular number.
Set the traffic percentage. This value is the minimum density at which the plan becomes active. A plan set to 50% will not appear with the relevant simulator traffic slider below 50%. Use 1% while diagnosing a new route.
Validate and compile. Correct unknown airports, overlapping legs, impossible timings and missing aircraft references. Compile specifically for FSX format and confirm that the tool produces a traffic .bgl; the uncompiled text or spreadsheet files are not read by the simulator.
Install the BGL. Put it in the scenery subfolder of an active scenery area. A dedicated location such as ...\Addon Scenery\My AI Traffic\scenery is easiest to manage once that area has been activated in the Scenery Library. ...\Scenery\World\scenery also works, but becomes harder to audit when many packages use it. Do not place traffic BGLs in SimObjects\Airplanes.
Restart and test. Restart FSX after adding or replacing the BGL. Raise both Airline traffic density and General aviation traffic density while testing, select the correct UTC date and load about 15 minutes before departure rather than exactly on the scheduled minute.

Parking behaviour is controlled by both aircraft and airport data. The aircraft's atc_parking_types, atc_parking_codes and physical size need a compatible parking spot in the airport scenery. A correct flight plan cannot create a gate that the airport does not have.

Why is my custom FSX AI traffic not showing?

Missing custom traffic is usually caused by a format conflict, an exact-title mismatch, the wrong time or a schedule whose density threshold exceeds the simulator setting.

Symptom	Likely cause and fix
No new FSX-format traffic appears	Search active scenery areas for legacy FS2004-format traffic BGLs. A single active FS2004 traffic file can prevent FSX-format plans from displaying. Back up and disable or convert the identified legacy file; do not remove stock FSX files at random.
The intended aircraft never appears	Compare the flight-plan aircraft reference with `title=` character for character, including spaces and punctuation. Also check for duplicate titles in other aircraft configurations.
The route appears at an unexpected time	The timetable is interpreted in UTC. Recheck the selected simulator date, the editor's weekly schedule settings and daylight-saving assumptions made when converting from local time.
The compiler reports an unknown airport	Add the airport's ICAO, coordinates and elevation to the compiler data, especially when the airport exists only in add-on scenery.
An arriving aircraft disappears or parks incorrectly	The airport may have no free spot of the correct size, type or parking code. Reduce competing traffic and test at a stock airport with suitable parking.
Flights or aircraft are duplicated	Two active BGLs contain the same plans, or both the original and edited versions are installed. Search every active scenery folder and retain only one copy.

A mistake we see constantly is testing a large schedule with several unknowns at once. Reduce it to one aircraft, two stock airports, a 1% daily return plan and high simulator traffic settings. Once that works, add airports, liveries and additional legs one at a time.

Can I use a flyable aircraft as AI traffic?

Yes, many flyable FSX aircraft can be assigned to AI schedules, but dedicated AI models are usually the better choice. Complex flyable models use more processing and graphics resources when dozens are visible, and some have animations or configurations that do not behave correctly under AI control.

The traffic BGL contains references and schedules, not the aircraft model or livery itself. Anyone receiving a shared traffic BGL must separately have an aircraft entry with the same title= value. When distributing a package, list those dependencies clearly and do not include aircraft or repaints unless their licence permits redistribution.