Enabling Developer Mode

Before you can access the powerful customization tools in Microsoft Flight Simulator, you must first enable Developer Mode. This feature is hidden by default to keep the main interface simple for casual pilots. Enabling it adds a dedicated toolbar and unlocks editors, consoles, and debug options that form the foundation of all serious modding and scenery creation.

To enable Developer Mode, follow these steps:

  1. Launch Microsoft Flight Simulator and wait for the main menu to load.
  2. Open the Options menu, located in the top‑right corner of the screen.
  3. In the left sidebar, select General.
  4. Scroll down near the bottom of the General settings panel until you see the Developer Mode toggle.
  5. Click the toggle so it switches to On.
  6. You may be prompted to restart the simulator. Confirm the restart if asked; otherwise, the new toolbar appears immediately.

Once Developer Mode is active, you will see a new toolbar at the top of the screen with icons for the DevMode Menu, the Scenery Editor, the Aircraft Editor, the Behaviors Editor, and a console button. Do not skip the restart even if the toggle appears to work instantly — some editors will not load correctly without a fresh session.

Understanding the Developer Toolbar

The toolbar is your command center for all customization work. Each icon opens a dedicated panel or editor. Hovering over an icon shows a tooltip with its name. The key components include:

  • DevMode Menu — A drop‑down panel with quick access to debug options, performance monitors, and the file explorer for project folders.
  • Scenery Editor — Used to place, modify, and test 3D objects, airports, and terrain elements.
  • Aircraft Editor — Allows you to inspect and modify aircraft configuration files, payload stations, and flight dynamics.
  • Behaviors Editor — For creating interactive cockpit logic, animations, and custom scripts.
  • Console — A command‑line interface for running Lua commands, viewing logs, and debugging package issues.

Each editor loads the currently active flight or project. You can switch between editors without restarting the simulator.

A Closer Look at the Scenery Editor

The Scenery Editor is one of the most powerful tools for customizing the visual world. It works with the Package Sources system introduced in the SDK. To create new scenery, you must first set up a project directory. From the DevMode Menu, select Open Package Sources and choose a folder where your custom assets will live.

Once a package source is defined, you can launch the Scenery Editor and begin placing objects from the library or importing your own glTF/OBJ models. Key features include:

  • Terrain elevation painting and flattening
  • Scenery object placement with rotation, scaling, and snap‑to‑surface tools
  • Runway and taxiway drawing
  • Light and shadow simulation previews

Tip: Always test your scenery by starting a flight nearby. Use the Reload Scenery option in the DevMode Menu to avoid restarting the simulator after every change.

The Aircraft Editor: Beyond Configuration Files

While many tweaks can be made by editing aircraft.cfg or flight_model.cfg in a text editor, the Aircraft Editor provides a visual interface for real‑time adjustments. You can access it from the toolbar when you are in a flight with the aircraft you want to modify. Changes made here can be saved to a custom package.

The editor is divided into several panels:

  • Systems — fuel, electrical, hydraulic, and pneumatic system parameters.
  • Flight Dynamics — aerodynamic coefficients, engine thrust curves, and landing gear behavior.
  • Payload & Stations — passenger seating, cargo holds, and weapon stations (if applicable).
  • Lighting — external lights, beacon positions, and brightness curves.

For a typical performance tweak like increasing engine power, locate the Turbine Engine or Piston Engine section, adjust the Thrust Scalar value, and save the changes. The simulator will apply them the next time you load the aircraft.

Working with the Behaviors Editor

The Behaviors Editor is for modders who want to add custom interaction logic — for example, a clickable switch that activates a custom light sequence or an animated gauge. Behaviors are written in an XML variant that references Template and Component definitions. The editor provides a syntax‑highlighted code view and a live preview window.

You can start from existing templates by selecting New from Template or clone a behavior from one of the default aircraft to understand the structure. Commonly used components include:

  • MouseRect — defines clickable areas on 2D panels or 3D cockpit meshes.
  • Animation — links numerical values to rotating or sliding parts.
  • Update — runs calculations every frame (e.g., for a custom autopilot).

Best practice: Keep behavior files modular. Create separate XML files for separate systems (e.g., autopilot.xml, lights.xml) and reference them from the main interior.xml or exterior.xml using the <Include> directive.

Practical Customization Examples

Example 1: Adding a Custom Scenery Object

Suppose you want to place a specific building model at your local airport. First, export your model as a glTF file with a .gltf extension and place it inside your package source folder under scenery/modelLib. Launch the Scenery Editor, click Add Object, browse to your model, and set its position on the apron. Use the Height Offset slider to sit it flush with the ground. Save the project as a new package (.fspkg) and install it via the DevMode Menu’s Install Package option. Reload scenery and you should see your building in the simulation.

Example 2: Modifying an Aircraft’s Fuel Capacity

Open the Aircraft Editor while flying the target aircraft. Navigate to the Payload & Stations panel. Locate the fuel tank stations (often named TANK_CENTER, TANK_LEFT_MAIN, etc.). Increase the Capacity field by 50% and adjust the Fuel Weight gauge accordingly to keep weight realistic. Save the configuration to a new variant in your package. Now when you spawn the aircraft, the fuel load will match your custom capacity.

Example 3: Debugging with the Console

The console can be opened by clicking its icon in the toolbar or pressing the backtick key (`). It accepts Lua expressions and exposes the global sim API. For example, to force‑print the aircraft’s current altitude every second, enter:

function tick()
  print(sim.get_altitude())
end
sim.register_tick_function("tick", 1.0)

To stop, press Ctrl+C or use sim.clear_tick_functions(). The console is also where you see error messages from misconfigured behaviors or scenery packages. Use it together with the Log Viewer (accessible from the DevMode Menu) to trace issues.

Best Practices and Warnings

Developer Mode gives you deep access to the simulator’s internals, but with great power comes the risk of corrupting your installation. Adhere to these rules:

  • Always back up original files before modifying any aircraft or scenery that ships with the base game. A single syntax error in a .cfg file can prevent that object from loading entirely.
  • Use the Package Sources system rather than editing files inside the official Official folder. Create a separate Community folder for your mods — this keeps your changes isolated and easy to remove.
  • Test incrementally. After every change, reload the relevant editor or restart the flight to see the impact. Trying to debug three or four changes at once makes finding the cause of a crash much harder.
  • Read the official SDK documentation for the exact schema of XML files and the limits of the physics engine. Many common pitfalls — such as mis‑specified animation ranges or invalid GUIDs — are clearly documented there.

Resources and Further Reading

To go beyond the basics covered here, refer to these official and community resources:

Conclusion

Developer Mode transforms Microsoft Flight Simulator from a polished out‑of‑the‑box experience into a modder’s playground. Whether you are adjusting the handling of a favorite aircraft, placing a landmark building at your home airfield, or building a complete custom scenery package, the tools described here give you the control you need. Start small — enable the mode, explore the editors, and modify one element at a time. As you gain familiarity with the XML structures and the editor interfaces, you will find that nearly every aspect of the simulator can be tailored to your vision. Keep backups, lean on the official SDK documentation, and share your creations with the community. The skies have never been more customizable.