General options

--help, -h

Display usage information about the most relevant command-line options and exit.

--verbose, -v

When combined with --help/-h, display usage information about all command-line options, not just the most relevant ones.

--version

Display version information about fgfs and some of the libraries used by the program (SimGear, OpenSceneGraph, PLIB), then exit.

--fg-root=path

Set the FlightGear data root directory ($FG_ROOT) to path. If this option is not set, fgfs uses the path specified in the FG_ROOT environment variable or, absent that, the FlightGear data directory chosen at the time the program was compiled.

--fg-scenery=path

Set the FlightGear scenery directories ($FG_SCENERY) to path.

You can specify multiple directories by separating them with colons (:), as in /first/path:/second/path (on Microsoft Windows operating systems, multiple paths should be separated by semicolons instead): in that case, fgfs will follow the order the paths are written in to search for scenery files, stopping as soon as a match is found.

If this option is not set, fgfs uses the path specified in the FG_SCENERY environment variable or, absent that, the Scenery subdirectory inside $FG_ROOT.

--fg-aircraft=path

Load additional aircraft from path besides the Aircraft subdirectory inside $FG_ROOT. Alternatively, you can use --aircraft-dir to target a specific aircraft in a given directory.

--download-dir=path

Store aircraft and scenery downloaded via the simulator in path.

The TerraSync directory may be specifically set with the --terrasync-dir option.

--allow-nasal-read=dirs

Allow Nasal aircraft scripts to read files from the directories listed in dirs (separate multiple paths with colons, or semicolons on Microsoft Windows operating systems).

By default, Nasal scripts are allowed to read data only from $FG_ROOT and $FG_HOME, as a security measure.

--read-only

Make $FG_HOME (the location where user-specific FlightGear data is stored) read-only.

--language=code

Set the language used by the simulator to code, where code is an ISO 639-1 two-letter locale code (for example, en or it).

--restore-defaults

Reset all user settings to their defaults.

--enable-save-on-exit, --disable-save-on-exit

Save/do not save user settings when the program exits.

--ignore-autosave

Ignore the user settings saved the previous time FlightGear was run. This option implies --disable-save-on-exit.

--browser-app=path

Use the Web browser specified in path to open aircraft documentation.

--prop:[type:]name=value

Set the property name to value. You can optionally specify the property type by setting type to string, double, float, long, int or bool.

--config=path

Load additional configuration directives from path. The file should follow the format described in fgfsrc(5).

--no-default-config

Do not load any configuration files unless they were explicitly specified with --config.

--units-feet

Use feet as the internal measure unit for distances.

--units-meters

Use meters as the internal measure unit for distances.

--console

Display a console window for simulator/aircraft debugging purposes.

This option is recognized only on Microsoft Windows operating systems; on other systems, debug messages are always printed to standard output/standard error.

--launcher

Start the FlightGear Launcher, a graphical Qt-based interface to the simulator.

This option is available only if FlightGear was compiled with Qt support enabled.

--json-report

Print a report in JSON format on the standard output. The report will give useful information for debugging purposes, such as the FlightGear version, the scenery/aircraft paths in use, the TerraSync and the data download directories and the paths to navigation data files.

Features

--enable-panel, --disable-panel

Enable/disable the pop-up aircraft instrument panel if the chosen airplane has it.

--enable-hud, --disable-hud

Enable/disable the heads-up display (HUD) if the chosen airplane has it.

--enable-anti-alias-hud, --disable-anti-alias-hud

Enable/disable heads-up display antialiasing.

--enable-hud-3d, --disable-hud-3d

Enable/disable the 3D version of the heads-up display.

--hud-tris

Display the number of triangles rendered when painting the heads-up display.

--hud-culled

Display the number of triangles culled when painting the heads-up display.

--enable-random-objects, --disable-random-objects

Show/hide random scenery objects, such as buildings. Scenery objects increase realism, but require more resources (memory and graphic card power).

--enable-random-vegetation, --disable-random-vegetation

Show/hide random vegetation.

--enable-random-buildings, --disable-random-buildings

Show/hide random buildings.

--enable-ai-models, --disable-ai-models

Enable/disable the internal AI subsystem, which is required for multiplayer gaming, AI traffic and many other animations. Disabling the internal AI subsystem is deprecated.

--enable-ai-traffic, --disable-ai-traffic

Enable/disable artificial plane traffic.

--ai-scenario=scenario

Add and enable the AI scenario scenario. This option may be repeated multiple times to enable multiple scenarios.

--enable-freeze

Start the simulator in a frozen (paused) state.

--disable-freeze

Start the simulator in a running (unpaused) state.

--enable-fuel-freeze

Do not consume any fuel (keep its quantity in the tanks constant).

--disable-fuel-freeze

Consume fuel normally.

--enable-clock-freeze

Do not let the clock advance while running the simulation.

--disable-clock-freeze

Let the clock advance normally.

--failure=pitot|static|vacuum|electrical

Fail the aircraft pitot, static, vacuum or electrical systems. This option may be repeated multiple times to fail more than one system.

--load-tape=tape

Load and replay the flight recorder tape tape.

Audio options

--show-sound-devices

Show a list of available audio devices and exit.

--sound-device=name

Set the sound device to use to name, where name is the device name shown by the --show-sound-devices option.

--enable-sound, --disable-sound

Enable/disable sound in the simulator.

Rendering options

--terrain-engine=tilecache|pagedLOD

Choose the terrain engine to use. tilecache is the "traditional" terrain engine (recommended); pagedLOD is a new, experimental terrain engine designed to minimize memory usage by loading more detailed versions of scenery objects on demand.

The pagedLOD engine is available only if FlightGear was compiled with GDAL support.

--lod-levels=levels

Set the level of detail levels to levels, where levels is a space-separated list of numeric levels. This option is available only if the terrain engine in use is pagedLOD.

--lod-res=resolution

Set the terrain mesh resolution to resolution. This option is available only if the terrain engine in use is pagedLOD.

--lod-texturing=bluemarble|raster|debug

Set the terrain texture method. This option is available only if the terrain engine in use is pagedLOD.

--lod-range-mult=multiplier

Set the range multiplier (the breakpoint from a low to a high level of detail) to multiplier. This option is available only if the terrain engine in use is pagedLOD.

--enable-rembrandt, --disable-rembrandt

Enable/disable the Rembrandt engine, which adds deferred shading (rendering all properties of an object, such as shading, lighting, fog) in more than one pass.

--renderer=name

If the Rembrandt engine is enabled, use the rendering pipeline described in $FG_ROOT/Effects/name.xml.

--enable-splash-screen, --disable-splash-screen

Show/hide the simulator splash screen while loading the aircraft/scenery.

--enable-mouse-pointer, --disable-mouse-pointer

Force enable display/do not force display the mouse pointer at startup.

--max-fps=frequency

Limit the maximum frame rate of the simulator to frequency Hz (frames per second).

--bpp=depth

Use a color depth of depth bits per pixel to display the aircraft and scenery.

--fog-disable, --fog-fastest, --fog-nicest

Choose the fog/haze rendering technique. --fog-disable will disable fog/haze entirely; --fog-fastest will explicitly ask the graphics card driver to choose the most efficient, but possibly less accurate, fog/haze rendering algorithm; --fog-nicest will leave the algorithm choice to the driver, leading to higher quality results.

--enable-enhanced-lighting, --disable-enhanced-lighting

Enable/disable enhanced runway lighting. This option is deprecated.

--enable-distance-attenuation, --disable-distance-attenuation

Enable/disable runway light distance attenuation (the runway lights become less intense as distance increases).

--enable-horizon-effect, --disable-horizon-effect

Enable/disable the celestial body growth illusion near the horizon.

--enable-specular-highlight, --disable-specular-highlight

Enable/disable specular reflections on textured objects.

--fov=degrees

Set the field of view angle (FOV) to degrees. High field of view angles allow you to see a wider part of the world; low angles allow you to "zoom in" on details.

--aspect-ratio-multiplier=factor

Set the horizontal and vertical aspect ratio multiplier to factor.

--enable-fullscreen, --disable-fullscreen

Enable/disable fullscreen mode.

--shading-flat, --shading-smooth

Use flat/smooth shading. If flat shading is active, the simulator uses the same color to paint the face of an object: this is faster, but makes edges more pronounced. Smooth shading smooths color changes between vertices, leading to higher-quality results, at an expense in performance.

--materials-file=file

Load the definitions of the materials used to render the scenery from file. By default, materials are loaded from $FG_ROOT/regions/materials.xml.

--texture-filtering=value

Set the anisotropic texture filtering to value. The acceptable values are 1 (default), 2, 4, 8 or 16.

--enable-wireframe, --disable-wireframe

Enable/disable the wireframe drawing mode (in which only object edges are painted).

--geometry=widthxheight

Set the window geometry (size) to widthxheight (both width and height are in pixels).

--view-offset=LEFT|RIGHT|CENTER|value

Specify the default forward view direction as an offset from straight ahead. The allowed values are LEFT (-90°), RIGHT (90°), CENTER (0°) or a specific number in degrees.

Aircraft options

--aircraft=name, --vehicle=name

Load an aircraft/vehicle from a set file named name-set.xml. The file is searched for in $FG_ROOT/Aircraft, in the directory pointed to by the environment variable FG_AIRCRAFT and in the directories passed to fgfs(1) using the --fg-aircraft option.

--aircraft-dir=path

Explicitly specify the directory in which the -set.xml file should be searched for. If this argument is used, the path cache stored in ~/.fgfs/autosave_X_Y.xml, the directories passed with the --fg-aircraft option and the directory specified in the FG_AIRCRAFT environment variable are not taken into account.

--show-aircraft

Print a list of available aircraft and exit.

--min-status=alpha|beta|early-production|production

Do not list aircraft having a status level (development status) lower than the one specified. See the FlightGear wiki "Aircraft rating system" page for an extended description of aircraft ratings.

--fdm=jsb|larcsim|yasim|magic|balloon|ada|external|null

Select the core flight dynamics model to use among the following ones:

--aero=name

Load the aircraft aerodynamics model from the file name.xml in the aircraft directory.

--model-hz=n

Run the flight dynamics model at a frequency of n Hz (n times per second).

--speed=n

Run the flight dynamics model n times faster than real time.

--trim, --notrim

Trim/do not attempt to trim the model. This option is only valid if the flight dynamics module in use is JSBSim.

--on-ground

Start the aircraft on the ground. This is the default option.

--in-air

Start the aircraft in the air. This option is implied if --altitude is specified.

--enable-auto-coordination, --disable-auto-coordination

Enable/disable auto coordination (joint control of rudder and ailerons).

--livery=name

Load the aircraft livery from a file named name.

--state=value

Set the initial aircraft state to value. The states that can be used are aircraft-dependent.

Time options

--timeofday=real|dawn|morning|noon|afternoon|dusk|evening|midnight

Start the simulator at the specified time of day:

--season=summer|winter

Load summer/winter textures.

--time-offset=[+|-]hh:mm:ss

Add a time offset to the startup time specified with the --timeofday option.

--time-match-real

Synchronize the simulator time with real world GMT time.

--time-match-local

Synchronize the simulator time with real world local time.

--start-date-sys=yyyy:mm:dd:hh:mm:ss

Specify the simulator starting date and time with respect to the local timezone of the system.

--start-date-gmt=yyyy:mm:dd:hh:mm:ss

Specify the simulator starting date and time with respect to the Greenwich Mean Time.

--start-date-lat=yyyy:mm:dd:hh:mm:ss

Specify the simulator starting date and time with respect to the timezone of the starting airport.

Initial position and orientation

--airport=ID

Start the simulator at the airport having ID as its ICAO code.

--parking-id=name

Place the aircraft at the parking position name. This option requires the --airport option to be present.

--runway=number

Place the aircraft on runway number. This option requires the --airport option to be present.

--carrier=name|ID

Place the aircraft on the AI carrier named name/having the ID ID.

--parkpos=name

Place the aircraft at the starting position name. This option requires the --carrier option to be present.

--vor=ID

Place the aircraft over the VOR ID.

--vor-frequency=frequency

Set the frequency of the VOR to frequency. This option requires the --vor option to be present.

--ndb=ID

Place the aircraft over the NDB ID.

--ndb-frequency=frequency

Set the frequency of the NDB to frequency. This option requires the --ndb option to be present.

--fix=ID

Place the aircraft over the fix ID.

--offset-distance=nm

Place the aircraft nm statute miles away from the reference point specified by the previous options.

--offset-azimuth=degrees

Place the aircraft at a heading of degrees degrees with respect to the reference point specified by the previous options.

--lon=degrees, --lat=degrees

Place the aircraft at the point with the coordinates (lat, lon). Northern longitudes/eastern latitudes must be positive; southern longitudes/western latitudes must be negative.

--altitude=value

Place the aircraft at an altitude of value feet (meters if the --units-meters option was specified).

--heading=degrees

Specify the initial heading (yaw) angle (psi) of the aircraft.

--roll=degrees

Specify the initial roll angle (phi) of the aircraft.

--pitch=degrees

Specify the initial pitch angle (theta) of the aircraft.

--uBody=units_per_sec

Specify the initial velocity along the body X axis.

--vBody=units_per_sec

Specify the initial velocity along the body Y axis.

--wBody=units_per_sec

Specify the initial velocity along the body Z axis.

--vNorth=units_per_sec

Specify the initial velocity along the body North-South axis.

--vEast=units_per_sec

Specify the initial velocity along the body West-East axis.

--vDown=units_per_sec

Specify the initial velocity along the body vertical axis.

--vc=knots

Set the initial airspeed of the aircraft to knots knots.

--mach=number

Set the initial airspeed of the aircraft to Mach number.

--glideslope=degrees

Set the flight path angle to degrees degrees. The value can be positive.

--roc=fpm

Set the initial rate of climb to fpm feet per minute. The value can be negative.

Route/waypoint options

--wp=ID[@alt]

Enter the waypoint (VOR, NDB, fix) ID into the autopilot. The optional part @alt can be used to specify the altitude at which ID should be crossed.

--flight-plan=file

Read a flight plan from file.

Avionics options

--com1=frequency

Set the COM1 frequency to frequency MHz.

--com2=frequency

Set the COM2 frequency to frequency MHz.

--nav1=[radial:]frequency

Set the NAV1 frequency to frequency MHz. You can optionally specify a radial by prefixing the frequency with the heading and a colon.

--nav2=[radial:]frequency

Set the NAV2 frequency to frequency MHz. You can optionally specify a radial by prefixing the frequency with the heading and a colon.

--adf1=[rotation:]frequency, --adf=[rotation:]frequency

Set the ADF1 frequency to frequency kHz. You can optionally specify the rotation angle of its compass card by prefixing the frequency with the angle and a colon. The --adf option is deprecated.

--adf2=[rotation:]frequency

Set the ADF2 frequency to frequency kHz. You can optionally specify the rotation angle of its compass card by prefixing the frequency with the angle and a colon.

--dme=nav1|nav2|frequency

Slave the automatic direction finder to the NAV1/NAV2 radio or set its internal frequency to frequency.

Environment options

--metar=METAR

Simulate the weather conditions described by the METAR string METAR. This option implies --disable-real-weather-fetch.

--enable-real-weather-fetch, --disable-real-weather-fetch

Enable/disable METAR-based real weather fetching. This feature requires an active Internet connection.

--enable-clouds, --disable-clouds

Enable/disable 2D (flat) cloud layers.

--enable-clouds3d, --disable-clouds3d

Enable/disable 3D (volumetric) cloud layers.

--visibility=meters

Set the initial visibility to meters meters.

--visibility-miles=miles

Set the initial visibility to miles miles.

--wind=dir[:maxdir]@speed[:gust]

Specify the direction the wind blows from (dir) and its speed (speed knots). If the wind is not meant to blow from a fixed direction, but rather from a range of directions, specify the range as dir:maxdir, where dir and maxdir are the minimum and maximum angles in degrees. If you want the simulator to model wind gusts as well, set gust to their maximum intensity in knots.

--random-wind

Randomize the direction and speed of the wind.

--turbulence=intensity

Set the turbulence intensity to intensity. The intensity can range from 0.0 (calm) to 1.0 (severe).

--ceiling=ft_asl[:thickness_ft]

Create an overcast ceiling at a height of ft_asl feet above the mean sea level. You can optionally specify a thickness by appending a colon (:) and the desired thickness in feet; if you omit it, the simulator will default to 2000 ft.

Network options

--callsign=value

Set the multiplayer callsign to value. The callsign must be at most ten characters long and must contain only numbers, letters of the English alphabet, dashes (-) and underscores (_); longer callsigns are truncated, and characters not matching those listed above are replaced with dashes.

--multiplay={in|out},hz,address,port

Specify the multiplayer communication settings.

The first field specifies whether the settings apply to inbound (in) or outbound (out) communications. The second field (hz) specifies the frequency (in Hz, times per second) at which data should be sent. The third field (address) must be set to the IP address of the network interface that FlightGear should use to send/receive data, or left blank to let the simulator use all available interfaces. The fourth field (port) should be set to the port to use (usually 5000).

--proxy=[username:password@]host:port

Specify the proxy server and port to use. The username and password are optional; if they are present, they should be given as MD5 hashes.

This option is only useful if --real-weather-fetch is enabled.

--httpd=[address:]port

Enable the Phi interface (HTTP server) on the specified address and port. The address is optional.

--telnet=port

Enable the Telnet interface on the specified port.

--jpg-httpd=port

Enable the screenshot HTTP server interface on the specified port. This option is deprecated: use the Phi interface instead.

--enable-terrasync, --disable-terrasync

Enable/disable automatic scenery/object downloads.

--terrasync-dir=directory

Set the directory where the downloaded scenery will be stored to directory.

--enable-fgcom, --disable-fgcom

Enable/disable the FGCom (voice ATC) integration.

I/O options

--generic=params, --atlas=params, --atcsim=params, --AV400=params, --AV400Sim=params, --AV400WSimA=params, --AV400WSimB=params, --garmin=params, --hla=params, --hla-local=params, --igc=params, --joyclient=params, --jsclient=params, --native-ctrls=params, --native-gui=params, --native-fdm=params, --native=params, --nmea=params, --opengc=params, --props=params, --pve=params, --ray=params, --rul=params

Open a connection to drive external programs or hardware.

Specify the protocol by using the correct command-line option:

Debugging options

--enable-fpe

Abort when a floating-point exception is encountered.

--fgviewer

View the scenery and the aircraft in a simple model viewer, without loading the entire simulator.

--log-level=bulk|debug|info|warn|alert

Set the minimum logging level. Log messages having a severity greater than or equal to the specified value are recorded; the others are discarded.

--log-class=all|none|ai|environment|flight|general|io|network|sound|terrain|...

Log only events belonging to the specified log classes (all logs all events, none logs none). Multiple classes can be specified by separating them with commas or pipes, for example: --log-class=ai,flight.

--log-dir=dir

Save the logs in the directory dir. If dir is desktop, the logs are saved on the Desktop. This option may be given several times, using a different directory each time. Inside the specified directory, the log file will be named FlightGear_YYYY-MM-DD_num.log, where YYYY-MM-DD is the current date and num is a progressive number starting at 0.

--trace-read=property, --trace-write=property

Trace the reads/writes for a property (print a log message whenever property is read from/written to).

--developer

Enable developer mode.