Custom flight scenarios in X-Plane transform the simulator from a passive flying experience into an active training or storytelling tool. While default scenarios offer standard conditions, the real power lies in crafting your own—whether for practicing instrument approaches in zero visibility, testing emergency procedures with simulated failures, or recreating a historic flight. X-Plane's open file structure and extensive scripting support allow you to control nearly every variable, from weather layers and time of day to aircraft systems and AI traffic. This guide walks you through the entire process, from understanding the scenario file format to writing Lua scripts that automate complex events. By the end, you will have the knowledge to build, test, and share scenarios that meet specific training or recreational goals.

Understanding X-Plane's Scenario Architecture

Before you create a scenario, you need to understand how X-Plane organizes and reads them. Scenarios are not compiled or encrypted—they are plain-text configuration files combined with a binary state file. This transparency makes manual editing straightforward.

All custom scenarios live inside the Custom Scenarios folder, which sits in the root X-Plane directory alongside Aircraft, Resources, and other folders. Each scenario is a subfolder with a unique name. Inside that folder, the essential files are:

  • scenario.txt – A text file that defines all scenario parameters: location, weather, aircraft, failures, and start settings.
  • situation.sit – A binary file that captures a precise snapshot of the aircraft's state (position, orientation, systems) at the moment the scenario was saved. X-Plane overwrites this file when you save a scenario in-sim.
  • Description.txt – Optional text that appears in the scenario selection menu, along with a thumbnail image named thumb.jpg or thumb.png.

The scenario.txt file uses a simple key-value syntax with section headers. A minimal file contains a BEGIN_LOAD_STRING section that points to an aircraft and a START_TIME entry for date and time. More complex scenarios include WEATHER, AIRCRAFT, MISSION, and GROUND_TRAFFIC blocks. You can edit this file with any plain-text editor; for syntax highlighting and validation, consider using VS Code or Notepad++ with the XML/Lua extension disabled.

Understanding this structure is the foundation. Every customization you make—from moving the aircraft 500 feet to the left to triggering an engine fire at 10 minutes—boils down to modifying values in these files or hooking into them with scripts.

Prerequisites and Tools

To customize and program scenarios with confidence, gather these tools and resources:

  • Plain-text editor – VS Code, Notepad++, or Sublime Text for editing scenario.txt. Avoid Word or other rich-text editors.
  • Coordinate data – Latitude and longitude for your starting location. You can get these from the X-Plane map, Google Maps, or an AIRAC database.
  • FlyWithLua plugin – Available from the X-Plane.org forums, this plugin lets you run Lua scripts that react to in-sim events (time, altitude, failures). It extends scenario programming far beyond what scenario.txt alone can do.
  • World Editor (WED) – Laminar Research's free tool for custom airports, ramp starts, taxi routes, and ground traffic. Use WED to design the environment around your scenario, such as placing temporary obstacles or custom parking positions.
  • Real-weather data source – Services like NOAA's Aviation Weather Center provide METAR strings you can paste into the scenario file for authentic conditions.

You do not need programming experience to build basic scenarios. The scenario.txt format is intuitive. For advanced scripting with FlyWithLua, basic Lua knowledge helps, but you can also install scripts written by others and adapt them to your scenario.

Creating a Custom Scenario from Scratch

The fastest way to create a new scenario is to duplicate an existing one and edit it. X-Plane ships with several default scenarios that you can use as templates. Navigate to X-Plane 12/Output/scenarios or X-Plane 12/Custom Scenarios depending on your installation. Locate a scenario folder such as SEA-Foggy, copy it, and rename the copy to My_Training_Scenario. Inside, rename the scenario.txt file header if needed.

Open the new scenario.txt. A typical file begins like this (shown as text):

BEGIN_LOAD_STRING
1: Aircraft/Laminar Research/Cessna 172 SP/Cessna_172SP.acf
-1: Custom Scenarios/My_Training_Scenario/situation.sit

START_TIME
2025-06-15 14:30:00

WEATHER
visibility 8.0 sm
surface_wind 220 12 kt
clouds 1000 3000 st

AIRCRAFT
lat 25.0
lon -77.5
altitude 2000.0 ft
heading 45.0
speed 110.0 kts

The BEGIN_LOAD_STRING tells X-Plane which aircraft to load (the first line) and which state file to use (the second line). The state file overrides the aircraft position if it exists. For a fresh scenario, you can remove the state file reference and let X-Plane use the coordinates from the AIRCRAFT block.

Edit the START_TIME to your desired date and time. For example, a night flight on New Year's Eve might read 2025-12-31 23:45:00. The weather block accepts multiple layers: visibility, wind, clouds, precipitation, and turbulence. Each parameter has its own line.

After making changes, save the file. Launch X-Plane, go to the Flight Configuration screen, select the Custom Scenarios tab, and you should see your scenario listed. Select it and click Start. If anything goes wrong, X-Plane writes errors to Log.txt in the root folder—check that file for clues.

Key Parameters in scenario.txt

Understanding the most common parameters gives you full control over your scenario's starting conditions. Here is a breakdown of the essential blocks:

START_TIME – Format is YYYY-MM-DD HH:MM:SS in 24-hour local time. X-Plane uses the system time zone. Set a specific date to simulate seasonal lighting and sun position.

WEATHER – One of the most powerful blocks. Key sub-parameters include:

  • visibility – In statute miles (sm) or meters. Use low values (0.5 sm) for fog, high values (50 sm) for clear days.
  • surface_wind – Direction in degrees true, speed in knots. Example: 250 15 kt means wind from 250° at 15 knots.
  • clouds – Three layers maximum. Syntax: base thickness type. Types include st (stratus), cu (cumulus), cb (cumulonimbus), and ci (cirrus). A broken layer at 3000 feet with 1500-foot thickness would be 3000 1500 br.
  • turbulence – Measured in feet per minute (fpm) vertical gust. 300 fpm is light chop; 900 fpm is severe. You can also use the body parameter for forces in g.
  • precipitation – Set rain or snow with an intensity value (0.0 to 1.0).

AIRCRAFT – Defines position and state before the situation file takes over. Parameters include lat and lon (decimal degrees), altitude (feet MSL or AGL), heading (true degrees), speed (knots indicated or true), gear (up/down), flaps (0‑full), and engines_running (1 or 0).

FAILURES – You can pre-set system failures in the scenario file. Example: eng_failure 1 would fail engine 1 on start. See the full list in the Laminar Research developer documentation for hydraulics, electrical, vacuum, and more.

Programming Weather and Environmental Conditions

Weather is the single most impactful variable in scenario design. A well-tuned weather block can turn a routine flight into a challenging instrument approach or a visual-flight nightmare. Beyond the basic parameters, you can inject exact METAR strings.

To use a real-world METAR, find one from a station near your chosen airport. For example: KLAX 031352Z 25015KT 6SM BR OVC010 17/15 A2992 RMK AO2. In the WEATHER block, replace the layers with a metar line: metar KLAX 031352Z 25015KT 6SM BR OVC010 17/15 A2992. X-Plane will parse this and apply the conditions exactly. Using METAR gives you realistic pressure, temperature, and dewpoint that standard parameters cannot achieve alone.

For dynamic weather progression, combine the scenario file with a FlyWithLua script. You can write a Lua loop that increments cloud cover every 60 seconds, simulating a front moving in. Or script a gradual wind shift that requires the pilot to recalculate drift. This type of programming elevates a static scenario into a training lesson.

Customizing Cloud Layers and Visibility

When building IFR training scenarios, precise cloud layering is critical. Use multiple cloud lines:

clouds 800 2000 ov (overcast from 800 to 2800 feet)
clouds 5000 1000 bk (broken layer from 5000 to 6000 feet)

The first layer might trap the pilot in a low overcast before breaking out at 5000 feet into a broken layer with scattered patches above. This matches real-world winter low-pressure systems. Test by loading the scenario and watching the altimeter as you climb through the layers. Adjust the base and thickness until the transition feels natural.

Visibility affects both visual references and AI aircraft rendering. Set visibility below 3 statute miles for IFR conditions, and pair it with light rain (rain 0.3) for realistic instrument training. For visual flights, keep visibility at 8 sm or higher, and use cumulus clouds at higher bases to avoid obscuring terrain.

Setting Aircraft Positions and Start States

Precise starting positions allow you to place the aircraft exactly where the scenario demands—on final approach, in a holding pattern, or taxiing on a specific ramp. The AIRCRAFT block uses decimal degrees for latitude and longitude. Get these from the X-Plane local map by zooming to your desired point and reading the coordinates at the bottom of the screen. Alternatively, use a tool like Little Navmap to export coordinates.

Altitude is interpreted as mean sea level (MSL) by default. To start 500 feet above ground level at an airport with elevation 200 feet MSL, set altitude 700.0 ft. For approach scenarios, calculate the altitude based on the glide slope. A 3-degree glide path from 5 miles out puts you at approximately 1500 feet AGL, so if the airport elevation is 300 feet, set altitude 1800.0 ft.

Heading and speed should match the phase of flight. An approach scenario might use heading 180 (runway heading) and speed 90 knots (approach speed for a C172). A cruise scenario could use heading 360 and speed 120 knots. The engines_running flag defaults to 1. For engine-start challenges, set it to 0 and include a failure on the starter or battery if desired.

Pre-Configuring System Failures

Failures transform a scenario from a flight into a test. Inside scenario.txt, add a FAILURES section:

FAILURES
eng_failure 1
vacuum_failure 1
fuel_quantity_failure 1

These fail the left engine (engine 1), vacuum pump, and fuel quantity gauge at scenario start. For timed failures, you must use a Lua script. For example, to fail the alternator 15 minutes after takeoff, write a FlyWithLua script that checks the flight time and triggers the failure using the command sim/operation/failures/electrical_alternator1.

Combine failures with weather: an alternator failure at night with low cloud forces the pilot to prioritize battery power and navigation equipment. This creates realistic emergency scenarios that build decision-making skills.

Designing Missions and Emergencies

Beyond a simple start point, you can chain multiple events into a mission-like sequence. X-Plane's scenario system does not have a built-in scripting language, but pairing the scenario file with FlyWithLua or using the MISSION block in scenario.txt (with limited conditions) allows for event-driven design.

The MISSION block can define objectives such as landing at a specific airport or reaching a certain altitude. For example, create a landing challenge that ends the scenario when the aircraft touches down outside the touchdown zone. These condition-checks run continuously and can display messages or trigger failures.

For more complex logic, use FlyWithLua scripts that run in the background. Write a script that monitors the aircraft's altitude and, when descending below 500 feet with gear up, plays a warning sound and shows a text message on screen. This kind of scripting makes scenarios interactive and forces the pilot to follow procedures.

Emergency scenarios should include a recovery path: if the pilot handles the failure correctly, the scenario progresses. If not, the failure escalates. For example, a fuel leak activates when the aircraft passes 10,000 feet. If the pilot switches to the opposite tank within 30 seconds, the leak stops. Otherwise, the engine sputters after 2 minutes. You script these conditions with timers and variables in Lua.

Advanced Customization with Lua Scripts

FlyWithLua is the primary tool for programming dynamic behavior that the scenario file alone cannot provide. After installing the plugin, create a Lua file in Resources/plugins/FlyWithLua/Scripts. The script runs whenever X-Plane loads a flight that includes that scenario.

Here is a minimal script that monitors the flight and shows a message when the aircraft exceeds 250 knots:

if PLANE_ICAO == "C172" then
  if sim/flightmodel/position/indicated_airspeed > 250 then
    sim/operation/message/show "Slow down! You are exceeding Vne."
  end
end

You can expand this to trigger failures conditionally. Create a timer using the sim/flightmodel/2/time/total_running_time data reference. Compare it to a threshold, and if the flight time exceeds 600 seconds (10 minutes), fail the engine using sim/operation/failures/eng_failure1.

For weather scripting, use sim/weather/ data references to change wind or clouds mid-flight. For example, reduce visibility suddenly at a specific latitude to simulate a fog bank. This gives you complete control and makes every scenario replayable with slight randomness.

Using World Editor for Detailed Environments

The World Editor (WED) lets you modify the airport layout where your scenario takes place. You can add ramp starts, define taxi routes, place temporary buildings, or even create custom ground vehicle paths using the GroundTraffic plugin. Although WED exports to X-Plane's apt.dat and dsf format, you can embed these files within your scenario folder.

To include a custom airport layout in your scenario, store the exported apt.dat in the Custom Scenarios/My_Scenario/Earth nav data directory. X-Plane will read this file when the scenario loads, allowing you to place the aircraft on a specific ramp start that only exists for that scenario. This is useful for training at fictional airports or for recreating construction zones with closed runways.

Testing and Debugging Your Scenario

After building your scenario, test thoroughly. Load it from the Custom Scenarios menu and verify each parameter: are the clouds at the correct height? Does the wind match your input? Are the failures active? Use the X-Plane instructor panel (Ctrl+I) to observe system states in real time.

If something does not work, check Log.txt in the X-Plane root folder. X-Plane writes detailed error messages for missing files, incorrect syntax in scenario.txt, and failures that could not be applied. Look for lines containing "scenario" or "failures." Common mistakes include missing a second colon in START_TIME (it must be exactly HH:MM:SS), using a comma instead of a space in the WEATHER block, or referencing an aircraft path that does not exist.

Iterate after each test. Change one parameter at a time and reload the scenario to isolate issues. Document your changes in a simple text log inside the scenario folder so you can revert if needed. This disciplined approach prevents frustration and ensures your scenario behaves reliably when shared.

Sharing Your Scenario and Community Resources

Once you have a polished scenario, share it with the community. Package the entire scenario folder as a ZIP file, include a descriptive title for the folder name (e.g., ILS_Approach_KJFK_Winter_Storm), and add a Description.txt file with your contact information, version, and a brief overview of the conditions.

Upload the ZIP to the X-Plane.org forums in the Scenarios & Missions section, or post it on resource sites like X-Plane.to and X-Plane.blog. In the description, list the required add-ons (such as specific aircraft or libraries) and the X-Plane version tested. Include a screenshot or thumbnail for visibility.

The learning continues when you explore scenarios created by others. Download community-made scenarios to see how experienced designers structure their files. Pay attention to how they layer weather, position aircraft, and script failures. You will often discover shortcuts and techniques that improve your own workflow.

Conclusion

Customizing and programming flight scenarios in X-Plane unlocks the simulator's full training and creative potential. You start by editing a few lines in a text file, and with practice, you build scenarios that simulate real-world conditions, test emergency procedures, and tell compelling stories. The combination of scenario.txt parameters, FlyWithLua scripting, and World Editor environment design gives you complete control. Begin with the weather and position parameters described here, then gradually incorporate failures and Lua-driven events. Each scenario you build will deepen your understanding of X-Plane's simulation engine and sharpen your own or others' flying skills.