Learn what SimConnect does in Microsoft Flight Simulator, which add-ons use it, when installation is needed, and how to fix failed connections.
SimConnect is Microsoft Flight Simulator's application programming interface (API) for exchanging simulator data and commands with add-ons and external software. It lets tools read aircraft state, position and weather, trigger simulator events, control compatible systems, inject traffic, log flights, and drive hardware such as instrument panels or motion platforms.
How does SimConnect work?
Microsoft Flight Simulator starts the SimConnect server as part of the simulator, while each compatible utility runs as a client. The client opens a connection and requests specific data rather than trying to extract information from the screen or simulator files.
A SimConnect client can typically:
- Read simulator variables such as latitude, altitude, airspeed, engine state, control positions and environmental conditions.
- Subscribe to changes at a chosen frequency instead of repeatedly requesting the entire simulator state.
- Send events and commands for supported controls, switches and simulator functions.
- Write permitted values, although many variables are read-only or restricted by the aircraft.
- Receive system events such as a flight loading, pausing or ending.
- Create or manage supported AI objects, which is useful for traffic applications.
The connection can remain on the same PC or operate across a local network when the client supports remote use. SimConnect is the communication layer; it is not an add-on manager, aircraft installer or standalone application.
What types of add-on use SimConnect?
SimConnect is used whenever an external application needs live information from Microsoft Flight Simulator or needs to send supported commands back to it.
| Type of add-on | Typical SimConnect use |
|---|---|
| Moving maps and flight trackers | Read position, heading, altitude, speed and flight status. |
| Flight loggers and analysis tools | Record routes, fuel use, touchdowns and aircraft states. |
| Hardware bridges | Drive gauges and displays, read switches and send cockpit control events. |
| Traffic utilities | Create, remove or monitor supported AI aircraft and ground objects. |
| Automation and performance tools | Monitor simulator conditions and adjust supported variables or settings. |
| Motion systems | Read attitude and acceleration data used to command a platform. |
Our explanation of how motion software converts MSFS telemetry into platform movement shows a practical hardware use for the interface.
Not every add-on needs SimConnect. Liveries and most scenery packages are loaded directly by the simulator, while aircraft may use in-simulator code and other APIs for their internal systems.
Do you need to install or enable SimConnect?
SimConnect is built into the PC versions of Microsoft Flight Simulator 2020 and Microsoft Flight Simulator 2024, so there is normally nothing to enable or install separately.
You usually install only the application that needs it. Some products include both an external executable and a package for the Community folder; both parts may be required, so follow that add-on's instructions rather than treating every SimConnect utility alike.
Older FSX-era applications can require a legacy SimConnect runtime alongside the version built into MSFS. A missing legacy dependency does not mean the simulator's own SimConnect server is absent. Our SimConnect installation and repair steps cover that distinction and the safest fixes.
For practical purposes, user-run SimConnect applications are a PC feature. Xbox Series X|S cannot run ordinary PC client executables, and neither can Microsoft Flight Simulator 2024 on PlayStation 5 or PS5 Pro. Do not assume that an application described only as SimConnect-compatible will work on a console.
Can SimConnect control every aircraft system?
No; SimConnect can control only the data and events exposed by the simulator or aircraft.
Default and relatively conventional aircraft often respond to standard events for items such as lights, landing gear, flaps and autopilot functions. Sophisticated add-on aircraft may store systems in local variables, input events, HTML/JavaScript components or proprietary code. An external client might therefore read altitude and position correctly while failing to operate a custom FMS or autopilot mode.
This is why hardware and utility developers often provide aircraft-specific profiles or bridge modules. A common mistake we see is blaming SimConnect when the requested cockpit function simply has no standard event behind it.
Is SimConnect the same as the MSFS SDK?
SimConnect is one development interface, whereas the Microsoft Flight Simulator SDK is the broader collection of tools and documentation used to build aircraft, scenery, airports, missions and other simulator content.
Ordinary users do not need the SDK to run a SimConnect application. Developers creating an external utility may use its SimConnect documentation and libraries; our guide to getting started with the wider MSFS SDK explains where external application development fits.
Why does a SimConnect add-on fail to connect?
A failed connection is usually caused by the client application's configuration, compatibility or dependencies rather than a disabled setting inside Microsoft Flight Simulator.
- Load an actual flight. Some clients connect at the main menu, but many remain on “waiting for simulator” until an aircraft is loaded and simulation data becomes available.
- Check simulator compatibility. Confirm that the application's release supports MSFS 2020 or MSFS 2024 as appropriate. Similar SimConnect APIs do not guarantee that every utility recognises both simulators.
- Install all supplied components. An external executable may depend on a matching Community package, plug-in or older runtime. Do not copy random SimConnect DLL files into simulator folders.
- Check network settings. A client on another PC needs the correct local IP address, port and firewall permission. Files such as
SimConnect.xmlandSimConnect.cfgshould be edited only when the application's instructions require remote configuration. - Restart both applications. Start Microsoft Flight Simulator, load the flight, and then reopen the client if it failed during simulator startup or an update.
- Isolate other clients. Close SimConnect utilities one at a time if several are connected and stutters, conflicting commands or repeated disconnections begin.
Does SimConnect need internet or affect performance?
SimConnect does not require an internet connection when the simulator and client run on the same PC. A remote client needs a network connection to the simulator PC, but that can be a private local network rather than the internet.
The interface itself normally has little noticeable performance cost. Problems arise when a poorly configured client requests large amounts of data at very high frequency, sends commands repeatedly, or runs alongside several other telemetry tools. If frame pacing deteriorates, close external clients individually before changing graphics settings or reinstalling the simulator.