Microsoft Flight Simulator and Lockheed Martin Prepar3D
Tacview has been tested and validated with the following editions of Flight Simulator:
Microsoft Flight Simulator 2024 (both retail & Steam editions)
Microsoft Flight Simulator 2020 (both retail & Steam editions)
Microsoft Flight Simulator X (both retail & Steam editions)
Lockheed Martin Prepar3D (v1 to v4)
To use Tacview with the above simulators, first, make sure you have downloaded and installed the latest version of Tacview. This will install MSFS2ACMI.exe and FSX2ACMI.exe on your computer.
Use
MSFS2ACMI.exefor Microsoft Flight Simulator 2020 and 2024, andFSX2ACMI.exefor all other versions, including Microsoft Flight Simulator X and Lockheed Martin Prepar3D.Launch
MSFS2ACMI.exeorFSX2ACMI.exefrom the Windows Start menu or search box. As long as it is running, all Flight Simulator flights will be recorded automatically.
To stop recording, close MSFS2ACMI.exe or FSX2ACMI.exe, or the simulator.
MSFS2ACMI.exe or FSX2ACMI.exe will automatically start a new recording when a major change is detected (such as a time or mission change).
All flight recordings are stored in:
%USERPROFILE%\Documents\Tacview
You can click the corresponding hyperlink in MSFS2ACMI.exe or FSX2ACMI.exe to open this folder:
The recording folder can be changed by going to Options → ACMI Files Recording Folder..
Real-Time Telemetry
Real-time telemetry is available with Tacview Advanced when using any version of Microsoft Flight Simulator, including FSX, Prepar3D, and MSFS. See the Real-Time Telemetry documentation.
Make sure you have launched C:\Program Files (x86)\Tacview\MSFS2ACMI.exe or C:\Program Files (x86)\Tacview\FSX2ACMI.exe before attempting real-time telemetry (or any flight recording)
SimConnect
Like many universal add-ons, FSX2ACMI.exe requires Microsoft Flight Simulator SimConnect to be properly installed in order to access telemetry data.
If SimConnect is not installed, you will receive the following pop-up:
If you are using Prepar3D, you must manually install SimConnect by running:
C:\Program Files\Lockheed Martin\Prepar3D v4\redist\Interface\FSX-SP2-XPACK\retail\lib\SimConnect.msi
If for some reason SimConnect is not installed with FSX, you should find its installer SimConnect.msi in a subfolder of FSX such as:
C:\Program Files (x86)\Steam\steamapps\common\FSX\SDK\Core UtilitiesKit\SimConnect SDK\LegacyInterfaces\FSX-XPACK\
Network Flights
MSFS2ACMI.exe and FSX2ACMI.exe do not differentiate between local and remote objects. Tacview displays everything exported by MSFS or FSX at a given time, which may or may not include other pilots.
Add-Ons (i.e. TacPack)
You can use MSFS2ACMI.exe or FSX2ACMI.exe with any add-on.
When used with TacPack, two recordings will be created: one from TacPack and one from MSFS2ACMI.exe or FSX2ACMI.exe.
The Tacview recorder usually provides better results, as it always supports the latest Tacview features such as advanced telemetry.
Terrain Elevation & Textures
To add terrain elevation files and textures, see [Customization].(../../customization/customization.md)
Can MSFS2ACMI.exe or FSX2ACMI.exe slow down my computer?
No. On modern systems, CPU usage is typically around 1% while recording. This was tested on a 2012 PC running FSX at maximum quality with 100% AI air and ground traffic (400–800 moving objects).
Running MSFS2ACMI.exe on a Remote Machine
Follow these steps to run MSFS2ACMI.exe on a different computer.
1. On the computer running Microsoft Flight Simulator
Ensure Flight Simulator is authorized in the firewall.
Locate the MSFS configuration directory, for example:
%LocalAppData%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache
Add the configuration file SimConnect.xml
Customize the file to use your preferred port and protocol, and set Scope = Global where applicable.
To verify connectivity, start a flight and run:
netstat -an -p tcp | findstr "0.0.0.0"
Confirm that your chosen port appears.
2. On the remote computer running Tacview and MSFS2ACMI.exe
Place the configuration file SimConnect.cfg next to MSFS2ACMI.exe:
Edit the file to use the host computer’s IP address and selected port.
3. Debugging
On the MSFS machine, add SimConnect.ini to:
%LocalAppData%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalState\
A debug console will appear whenever SimConnect starts.
You can also enable Developer Mode, then open Tools → SimConnect Inspector to view active connections.
More resources
Heading mismatches
Significant heading mistmatches may be observed in FSX. The problem is caused by a difference in magnetic variation between Tacview and FSX.
The latest official version of FSX uses an old magnetic variation map, from around 2009.
Tacview uses the International Geomagnetic Reference Field, IGRF, to calculate the proper magnetic variation for the selected flight date. This data is based on the IGRF-14 coefficient file published by NOAA/NCEI.
The IGRF model is available from NOAA/NCEI.
For example, if you fly in 2026 in FSX, FSX will still use its old 2009 magnetic variation data. Tacview, however, will use the proper 2026 magnetic variation. This can create a visible heading offset between FSX and Tacview.
To verify the problem in FSX, you can press Shift+Z several times to cycle the on-screen information overlay. This can display the aircraft heading directly on screen, which is usually easier to read than the analog cockpit instruments and helps avoid diagnostic mistakes.
There are two practical solutions.
The first solution is to fly in FSX using a 2009 date. This makes Tacview use the same approximate magnetic variation period as FSX.
The second solution is to update the FSX magnetic variation file to a modern one, such as the 2026 file provided by Hervé Sors:
https://www.aero.sors.fr/navaids.html
https://www.aero.sors.fr/hfiles/MagDec_Update.zip
To install it, copy MAGDEC.BGL from the update package to the FSX scenery folder. For FSX Steam Edition, this is typically:
C:\Program Files (x86)\Steam\steamapps\common\FSX\Scenery\Base\Scenery\
For other FSX installations, use the equivalent folder described in the documentation.
More details about the problem and the fix are available in Hervé Sors’ documentation.
Note that replacing MAGDEC.BGL improves the magnetic variation used by FSX globally, but it does not necessarily update runway numbers, airport scenery data, ILS definitions, or add-on aircraft databases. Some of these may have their own magnetic data baked in.
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