> For the complete documentation index, see [llms.txt](https://raia-software-inc.gitbook.io/tacview/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://raia-software-inc.gitbook.io/tacview/flight-simulator/msfs-p3d.md).

# Microsoft Flight Simulator and Lockheed Martin Prepar3D

Tacview has been tested and validated with the following editions of Flight Simulator:

* [Microsoft Flight Simulator 2024](https://store.steampowered.com/app/2537590/Microsoft_Flight_Simulator_2024/) (both retail & Steam editions)
* [Microsoft Flight Simulator 2020](https://store.steampowered.com/app/1250410/) (both retail & Steam editions)
* [Microsoft Flight Simulator X](https://store.steampowered.com/app/314160/) (both retail & Steam editions)
* [Lockheed Martin Prepar3D](https://www.prepar3d.com/) (v1 to v4)
* [VRS TacPack & Superbug](https://www.vrsimulations.com/)

To use Tacview with the above simulators, first, make sure you have downloaded and installed the [latest version](https://tacview.net/download/) of Tacview. This will install `MSFS2ACMI.exe` and `FSX2ACMI.exe` on your computer.

* Use `MSFS2ACMI.exe` for Microsoft Flight Simulator 2020 and 2024, and `FSX2ACMI.exe` for all other versions, including Microsoft Flight Simulator X and Lockheed Martin Prepar3D.
* Launch `MSFS2ACMI.exe` or `FSX2ACMI.exe` from the Windows Start menu or search box. As long as it is running, all Flight Simulator flights will be recorded automatically.

![MSFS - Launch MSFS2ACMI.exe or FSX2ACMI.exe](/files/PU5tUkYpNMdi0GhncXG8)

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:

![MSFS - ACMI Files Hyperlink](/files/PKdp8ttsbTQD0ST46q2h)

The recording folder can be changed by going to `Options` → `ACMI Files Recording Folder..`

![MSFS - Recording Folder](/files/PJ9tciS6SsIscDiq7pWc)

### 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](https://github.com/RaiaSoftwareInc/tacview.documentation/blob/main/standard-and-advanced-features/real-time-telemetry.md#with-dcs-world-x-plane-or-microsoft-flight-simulator).

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:

![SimConnect not installed](/files/yIqT8OLio5EXl2jtUS3j)

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](https://www.vrsimulations.com/), 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](https://ln5.sync.com/dl/6b7cdbce0#ek2ej7x2-zkemh6xj-g5gg2bcc-ry9na5sb)

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](https://ln5.sync.com/dl/4e2fe6cc0#d9xqhkgd-ieatbktc-bkrbkk53-zgugnsat) 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](https://ln5.sync.com/dl/e0ae8a830#vdmngyim-ffgc4iy8-magfmuki-ym94g4hp) 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

[SimConnect SDK documentation](https://docs.flightsimulator.com/html/Programming_Tools/SimConnect/SimConnect_SDK.htm)

### 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](https://www.ngdc.noaa.gov/IAGA/vmod/coeffs/igrf14coeffs.txt) published by NOAA/NCEI.

The [IGRF model](https://www.ncei.noaa.gov/products/international-geomagnetic-reference-field) 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](https://www.aero.sors.fr/documentation/MVReadme.pdf).

More details about the problem and the fix are available in Hervé Sors’ [documentation](https://www.aero.sors.fr/documentation/MVReadme.pdf).

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.