Frequently asked questions

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Thank you for downloading FlightGear! This FAQ lists some of the most commonly asked questions. Please create a topic at our forum if you cannot find the answer on your problem(s).

Contents

The FAQ

Where can I get the latest version of this FAQ?

http://wiki.flightgear.org/index.php/FAQ

Who do I contact if I have comments about this FAQ?

Add your comment to this FAQ's discussion page.

How old is this document?

Check its history.

What other important documentation should I read?

Distribution

Where can I get FlightGear?

The official download page is http://www.flightgear.org/download/. Source code is our primary form of distribution, but precompiled binaries are available for Windows and SGI IRIX.

Alternatively, FlightGear is packaged for Linux by SuSE, Debian and Mandrake, and can be directly installed through those distributions via any package manager.

How do I install FlightGear on Ubuntu?

FlightGear 2.0.0 can be installed directly from the Synaptic Package Manager for Ubuntu 11.04 onwards. Open Synaptic Package Manager, search for FlightGear and follow instructions. FlightGear 2.4.0 is available as a GetDeb package for Ubuntu 11.04 onwards. Install GetDeb on your Ubuntu machine and install FlightGear from PlayDeb's website.

What is the password for the FTP server?

The FTP server uses standard anonymous login procedures. Login with the username "anonymous" and use your email address as the password. Most FTP clients and web browsers will do this automatically for you.

Why won't the FTP server let me in with the right login info?

This generally means that the server is at its capacity. You should receive a message saying such, but your FTP client may be hiding it from you. Your options are to keep trying until a slot opens up or try connecting to one of our FTP mirrors listed at http://www.flightgear.org/mirrors.html.

Where can I find the latest development source code?

1rightarrow.png See Flightgear and Git for the main article about this subject.

The latest development code is available for everyone through our Git repository.

Why are the aircraft at FlightGear.org out of date?

The official aircraft downloads are only updated at the time of a new release of FlightGear. This is done because aircraft that are currently in development are usually developed on development/unreleased versions of FlightGear. Those development versions have lots of features that are not supported by the (older) stable release. Would we update the aircraft downloads more often; most aircraft won't work on the stable release of FlightGear.

What is SimGear, and why do I need it?

SimGear is a library of supporting code. SimGear is only needed if you plan on compiling FlightGear — it is not needed to run precompiled binaries. For more information see http://www.simgear.org/. Note: When compiling FlightGear it is very important to have the matching version of SimGear.

Where can I fly and where do I get the scenery?

While the base package only comes with scenery for the San Francisco Bay area, you can currently fly just about anywhere in the world. See the "Additional Scenery" section of http://www.flightgear.org/download/ for more information or go directly to our graphical downloader at http://www.flightgear.org/Downloads/scenery-1.0.1.html

Terrasync is an option too. It downloads the latest scenery while flying. In 2.4.0 a GUI for enabling/disabing Terrasync can be found at Environment->Scenery Download.

Also visit our "Places to Fly" section of the website (http://www.flightgear.org/places.html) for some help navigating to some awesome locations. (see also Installing Scenery)

Where can I get different 3D models for my plane?

Official FlightGear aircraft can be found at http://www.flightgear.org/download/aircraft-v2-4/ . Other aircraft in development can be found on Git, and some other aircraft can be found on 3rd party FlightGear hangars.

How current is the data in FlightGear compared to the real world?

We use the same navaid and airport dataset that X-Plane uses. The current dataset can be found in the $FG ROOT/Navaids/ and $FG ROOT/Airports/ directories. If you have updates or corrections to the dataset, see http://www.flightgear.org/Docs/AirNav/AptNavFAQ.FlightGear.html for instructions on contacting the database maintainer.

Where is the moving map?

A popular moving map display is available under a separate project called Atlas. Also, MPmap is an online map for multiplayer.

If you like an alternative to Atlas with updated graphics and mapping provided by the OpenStreetMap project, then check out Flightgear Mapping fgmapping or JMapView.

Why don't you charge money for this?

FlightGear can be downloaded for free from many locations including the FlightGear website, but can also be bought on a CD. Although we offer that service (see the website), we encourage other groups to redistribute it for their users, especially within an operating system distribution which makes installation even faster and easier for new users.

Occasionally you may see FlightGear for sale on auction sites or commercial websites under some other name. This can be done quite legitimately as long as the terms of the license are upheld and might be worth the cost if some value-added features such as additional scenery, aircraft or after-sale support are included. Unfortunately, most cases seen to date appear to be just someone trying to make money selling something that is free and providing no real added value.

How can I get started with FlightGear

The latest release of FlightGear can be downloaded at the download central, but most aircraft need to be separately downloaded here and installed manually. Be aware of system requirements! Also, check out New to FlightGear.

Compiling

1rightarrow.png See Building Flightgear for the main article about this subject.

Why won't FlightGear compile?

Well, that depends. First make sure you are using the appropriate versions of FlightGear, SimGear, plib, zlib. If any of the packages are out of sync with the others, compilation may fail. See also Building FlightGear

The FlightGear Downloads page should tell you what versions you need if you are trying to compile the latest stable release. If you are using a development snapshot, make sure all three packages are up-to-date.

Also ensure that you have some implementation of OpenGL with glut support with the appropriate header files. Linux users with nVidia cards should make sure you have the latest drivers from nVidia. Other Linux users make sure you have Mesa3D (http://mesa3d.org/) and your X server installed correctly.

If your problems persist, ask in the FlightGear Forums, on the IRC or subscribe to our FlightGear-Users mailing list and let us know what problem you're having.

Configuring

How do I install new scenery?

1rightarrow.png See Howto: Install scenery for the main article about this subject.

The scenery archive files (ie. w100n30.tar.gz) should be untarred into the Scenery/Terrain directory in your $FG_ROOT.

How do I setup my joystick(s)?

1rightarrow.png See Joystick for the main article about this subject.

FlightGear should come with a helpful program called `fgjs` that can help configure your joystick. Run `fgjs` and then copy the dot file it created into your home directory or add its contents to your existing rc file.

Also, see the $FG_ROOT/Docs/README.Joystick file located in the FlightGear base package and the joystick page on the wiki.

What format should my personal .fgfsrc file be in?

Your .fgfsrc file should simply be a list of command line options with one option per line. The file is not an XML file.

If you would rather use an XML configuration file, you can add something like the following in your .fgfsrc

--config=/path/to/my/config.xml

Almost every option corresponds to a property, so you can choose to use whichever method best suits your needs.

Running

If you get errors in the console (black window), please check Howto: Understand console output and see if your error is listed (with a solution).

Unable to execute file: bin/Win32/fgrun.exe during installation

Your system is missing the MSVC runtime libraries required by FlightGear. Download and install the following vcredist_x86.exe:

Why do I get an error loading libopenal.so.0?

With the default installation, libopenal.so.0 is installed into /usr/local/lib. You need to ensure that that path is listed in /etc/ld.so.conf, then run `ldconfig`as root.

Why do I get "ssgInit called without a valid OpenGL context"?

In short, your GL libraries are broken. So far only Red Hat 7.x users have experienced this (see http://www.redhat.com/bugzilla/show_bug.cgi?id=18867). The only solutions are possibly complicated ones: you can either change distributions (most of us prefer Debian) or upgrade/downgrade your Mesa libs.

Why do some other GL applications work though? Well, Steve Baker (Mr. PLIB) has explained this on the plib-users list (http://www.geocrawler.com/lists/3/SourceForge/1867/0/6470648/).

What happened to the panel, keyboard, etc?

The problem is almost certainly that your base package is out of sync with FlightGear. Many configurable parts of FlightGear are defined in XML files contained in the base package.

Why doesn't audio work properly under Irix?

FlightGear (as of June 2001) uses the Portable Libraries (PLIB) for playing audio. The audio queue implementation of PLIB is far from optimal (in fact it's just wrong). This seems to work on other platforms quite well, but Irix expects things to be programmed properly.

There has been discussion about using OpenAL (http://www.openal.org/) for the next release of both PLIB and FlightGear. Tests show that the OpenAL audio implementation does the job right, meaning that these audio problems should be gone by then. In the mean time it is best to disable audio on Irix completely (by adding --disable-sound either on the command line or to your $HOME/.fgfsrc file).

Why is FlightGear so slow?

1rightarrow.png See Howto: Improve Framerates for the main article about this subject.

FlightGear supports hardware acceleration, but it seems not to be activated. Make sure you have OpenGL libraries installed and configured properly and make sure you have the latest drivers for your video card.

Linux users: If you are an nVidia user, follow their directions on getting your card working. For most other users, make sure Mesa is installed property and ensure that you have the appropriate kernel device drivers for your card. Most people (and distributions) use modules for their video card device drivers; run `lsmod` as root to see what modules are loaded. You should also make sure that you are loading the appropriate modules in your XF86Config and that your video device section is correct. Now try running an OpenGL application (other than FlightGear) to see how it performs. You can try the gears demo from Mesa or something like Quake3.

Why is my SGI machine so slow?

First of all, one of the most common mistakes on SGI hardware is to forget to specify --fog-fastest. On most SGI machines the EXP2 shading model isn't hardware supported resulting in frame rates below 1 frame per second (fps).

FlightGear makes extensive use of the OpenGL z-buffer feature,which on most older SGI hardware is only supported in software. This means that the CPU has to do all the z-buffer calculations in addition to the other tasks FlightGear involves (flight dynamics, scenery tracking, pushing commands into the graphics queue, etc). The following features are software rendered on low-end SGI machines (like Indy and Indigo):

  • stencil and accumulation buffer
  • depth queuing and depth buffering
  • fogging, lighting, clipping and transforms
  • texturing

This means that running FlightGear with the following options may not even get the desired result:

./runfgfs --fog-disable --shading-flat --disable-skyblend  --disable-textures --disable-clouds --disable-sound --disable-panel --enable-hud --disable-anti-alias-hud

I could even imagine that adding --enable-wireframe doesn't work on these machines (I would be happy to be proven wrong though).

On a machine like O2 the following options give an acceptable result:

./runfgfs --fog-fastest --disable-sound

Since I don't have access to other SGI hardware I can't tell which options would be appropriate for your situation.

How do I see the Frame Rate?

On the in-sim menu select View > Display Options, then check the box that says "Show frame rate".

How do I toggle panel settings?

There are two ways. One way is to hide the panel without the HUD showing. To hide the panel, use Shift+P; To make the HUD disappear, use H. The second way is to use the alternative HUD by Shift+I (Use I to switch back).

Stuck upside down after "crash"?

In his infinite wisdom the FlightGear Grand Master decided that planes were too valuable to allow them to be destroyed by novice pilots who seemed to crash a lot. The fact that nobody has bothered to model crashes may have something to do with it too. :-)

The result of this as you have noticed is that with a little practice an ingenuity you can trim the ship to fly inverted along the ground. The quick answer is to reset the sim, via the File > Reset menu. This will place your aircraft back at its starting location.

For the stubborn people out there: The trick to learn is to roll back to normal (non inverted) do this by nursing the elevator to get to about 500 feet or so and use the ailerons to snap roll 180*. This is all good avionics except for the plane not destroying itself. Remember the controls work in reverse when you are inverted and keep that airspeed up!!!

Why does FlightGear die on startup saying "time zone reading failed"?

This is probably caused by a line-ending problem in the timezone files. Win32 users can resolve the problem by downloading a DOS to UNIX conversion utility available at http://www.nottingham.ac.uk/~eazdluf/d2u.zip. Run as `d2u *.tab` from within the timezone directory to fix your timezone files.

Why won't the latest versions of some aircraft work in my (older) version of FlightGear?

Often new aircraft development keeps pace with the latest FlightGear code development. New or newly modified aircraft may rely on files (such as new instrument files) or features, only available with newer versions of FlightGear. If you are stuck with an older version of FlightGear, you can try downloading an earlier version of the aircraft at one of the archives:

Why are my screenshots black?

Make sure you have multithreading disabled in $FG_ROOT/preferences.xml. Enabling it currently breaks the screenshot function.

Flying

Why won't my engine(s) start?

Aircraft vary in their starting procedure. Some may have an auto-start sequence menu entry or instructions in the aircraft help menu (Press "?") and/or at the aircraft's wiki.

Starting engine in single-engine aircraft

In general to start the engine on a piston-engine type aircraft, you need:

  1. Fuel - You can run out of fuel, of course, but for certain aircraft, FlightGear may load it with no fuel, making it impossible to start the engines. Check this in the menu Equipment > Fuel and Payload.
  2. Correct mixture (generally "rich", ie red knob all the way in)
  3. Magnetos on (R, L, or both--generally select "both")
  4. Throttle (some engines start better with a little gas)
  5. Hold starter for sufficient time.

You may be able to do all these functions with the standard 2-D panel or your aircraft's built-in panel. However using the standard key bindings is more reliable:

  1. Press/hold "m" to set mixture to rich (m=rich, M=lean--if you are at a very high elevation you may need to set it somewhere besides full rich)
  2. Press "}}}" (three times) to set magneto to R, L, and finally "Both".
  3. Open throttle a little.
  4. Press "s" to run the starter. For some aircraft you may have to hold "s" as long as 10 seconds before the engine starts.

These instructions may not work for jet aircraft, helicopters, or other types of aircraft with complex start procedures. Check the instructions in the aircraft help menu (Press "?") and/or at the aircraft's wiki.

Starting engine in multi-engine aircraft

Starting all engines in a multi-engine aircraft is similar to the single engine--except you must follow the same start sequence for each and every engine. Flightgear provides a convenient way to do this for all engines at once.

Note that the default 2-D panel is connected to only one engine. So if you try to start the engines using the 2-D panel controls you will most likely start only one engine.

Instead, use the keyboard to start all engines at once:

  1. Press "~" (select all engines)
  2. Press/hold "m" to set mixture to rich (m=rich, M=lean--if you are at a very high elevation you may need to set the mixture somewhere besides full rich)
  3. Press "}}}" (three times) to set magnetos to R, L, and finally "Both".
  4. Open throttle a little (it now controls all engines).
  5. Press "s" to run the starter (it now runs the starter on all engines). For some aircraft you may have to hold "s" as long as 10 seconds before the engine starts.
  6. Rev the engines a little with your throttle and check your tachometers and/or visually to be sure all engines are running.

If the engines won't start, make sure you have fuel. Some aircraft have switches to control which fuel tanks feed which engines, so check these. Make sure each engine you want to start is connected to a tank that has fuel. Check fuel tanks in the menu Equipment > Fuel and Payload.

These instructions may not work for jet aircraft, helicopters, or other types of aircraft with complex start procedures. Check the instructions in the aircraft help menu (Press "?") and/or at the aircraft's wiki.

Where can I learn about instrument flying and navigation?

1rightarrow.png See Understanding Navigation for the main article about this subject.

What is the difference between Aileron and Rudder?

There is a bit of info on aileron vs. rudder in the very same book...

Is there support for multi-player flying?

1rightarrow.png See Howto: Multiplayer for the main article about this subject.

Yes. Both the Windows and *nix versions of FlightGear are capable of multi-player flying on FlightGear servers.

A map showing players aircraft online in real time is available as MPmap.

Where are the best places to fly in FlightGear?

FlightGear scenery covers the whole world, but thanks to the FlightGear user community, certain airports and areas are more detailed than others. For a full list of airports with buildings available in the default scenery, visit the forum's of improved airports.

  • There are a lot of high-quality scenery models around Paris, France.
  • EHAM Amsterdam Schiphol, EGKK London Gatwick and LFPG Paris Charles de Gaulle are some of the highest quality airports in FlightGear.
  • TNCM St. Maarten is a popular destination, and the surrounding islands (Anguilla, St. Eustatius, Saba, St. Barthélemy, St. Kitts, and Nevis) are all well-modeled.

Furthermore, there is a special wiki page with a list and preview of good Places to fly.

Where can I find airport info and aeronautical charts online?

1rightarrow.png See Getting aeronautical charts for the main article about this subject.

A world-wide database of airports and navaids can be found at World Aero Data.

Two very good US-only sources are

Is there support for any military scenarios like dog fighting or bomb dropping?

Most of our developers are primarily interested and focused on civilian aviation. We aren't explicitly excluding these features — we just haven't had anyone who has done much development in these areas until recently. Now there are third-party bombing scenarios for the A-10 and other aircraft with armament, like the North American OV-10A Bronco, General Dynamics F-16 and F-117 Nighthawk.

A new add-on (9/2009) adds support for dogfighting (including multiplayer dogfighting) and bombing scenarios.

Why are my controls returning to a particular position?

There are several possibilities that can lead to this:

  • If your aircraft's autopilot is enabled, it will take over (some of) your controls. Switch the autopilot off to regain control.
  • Some laptops have an onboard gravity sensor, that might be detected by FlightGear as a joystick. You can set FlightGear to ignore this fake-joystick:
    1. Get your accelerometer's name via the in-sim Help > Joystick Information dialog.
    2. Add this name to your $FG_ROOT/Input/Joysticks/Accelerometers/accelerometers.xml file, enclosed by <name> and </name> tags..
    3. Report your device name to #flightgear at irc.flightgear.org, so it can be included in the "official" accelerometer.xml file.

Why does my panel disappear when looking around?

2D panels are often only visible while looking in a fixed direction. At FlightGear, we prefer 3D cockpits, so most aircraft have those. The Cessna C172P is an example of an aircraft that has various variants, including a 2D and 3D one. Make sure you pick the 3D one (--aircraft=c172p).

Hacking

What language is FlightGear written in?

Mostly C++ with some supporting C code that's primarily contained within SimGear.

See the code analyses at Ohloh for more details on the used languages:

How do I design a flight dynamics model for a new aircraft?

FlightGear supports various flight dynamics models (FDMs), but just two of them are commonly used:

  • JSBSim: see http://jsbsim.sf.net/.
  • YASim: if you want a simpler FDM to work with, try your hand at YASim. For a guide on creating YASim aircraft, look in the FlightGear base package for $FG_ROOT/Docs/README.yasim.

UIUC is also available, but the main and most used ones are JSBSim and YASim.

How do I import planes from Microsoft Flight Simulator?

You can import planes by using the 3D Convert utility which will convert the MSFS 3d model to a format used by FlightGear. You have to add the animations and parts.

Also, although you can import the 3D model and textures, the flight dynamics (the .AIR file) must be completely redone for FlightGear.

If you wish to import a model made with gmax, you will need to convert it to .MDL format using Microsoft's MakeMDL SDK which is available at http://zone.msn.com/flightsim/FS02DevDeskSDK08.asp.

How do I design or modify a panel?

See the README.xmlpanel file located in the FlightGear/docs-mini/ directory of the source distribution.

How do I place objects, like buildings, into FlightGear?

1rightarrow.png See Portal:Developer/Scenery for the main article about this subject.

First, ensure that you have v0.7.7 or later, the scenery files where you plan to place the object, the actual model, and the longitude and latitude where you plan to place the object.

Now get the altitude for your point. If you don't want to calculate this yourself, start FlightGear at your location and take note of the altitude. Here's an example command:

fgfs --lat=45.50 --lon=-75.73 2>&1 | tee fgfs.log

The altitude is probably in feet, so divide the starting altitude by 3.28.

Search the output log file for the first occurrence of the string "Loading tile" and take note of the filename. In the above example, the output line looks like:

Loading tile /usr/local/Scenery/w080n40/w076n45/1712601

Copy a 3D model in a format that Plib understands to the same directory as the tile file. Edit the text file in that directory consisting of the tile name with the extension ".stg". The file will already exist if there is an airport on the tile; otherwise, you can create it from scratch. In our example, the filename is:

/usr/local/Scenery/w080n40/w076n45/1712601.stg

At the end of the file, add a new entry for your object, consisting of the word "OBJECT_STATIC" followed by the model name, the longitude in degrees, the latitude in degrees, the altitude in meters, and the heading in degrees. In our example the line looks like:

OBJECT_STATIC Towerax.ac -75.73 45.40 60 0

Save the changes to the .stg file, restart FlightGear, and enjoy.

NOTE: The above information was taken from the following mailing list post: http://www.geocrawler.com/archives/3/11854/2001/6/0/5991409/. See that page if this one doesn't make sense.

An alternative approach using PPE is described at http://mail.flightgear.org/pipermail/flightgear-devel/2001-December/002239.html by Norman Vine.

Since Flightgear 0.9.10 there is an easy way for Placing 3D Objects with the UFO.

Where can I learn 3D programming and how do I get involved?

Contributing to the 2D panel doesn't require any coding at all, just a minimal knowledge of XML syntax (i.e. five minutes' worth) and good skills with drawing and/or paint programs. Every instrument on the current panel, with the partial exception of the magnetic compass, is defined entirely in XML with no custom C++ code. If you want to get started, take a look at John Check's excellent intro at $FG_ROOT/Docs/README.xmlpanel.html.

Likewise, if you want to create a 3D cockpit for FlightGear, or to create buildings, external aircraft models, etc., your help is *desperately* needed. The only rule is to go easy on the triangles -- a model with 50,000 triangles probably won't be usable in FlightGear, and one with 5,000 triangles, only marginally. If you can design a nice 3D cockpit interior for in a 3D design program such as AC3D, Blender or PPE and you can write some XML code, it will be much appreciatted.

If, on the other hand, you really want to get your hands dirty with C++ coding, you'll have to buy a good OpenGL book eventually. However, FlightGear uses OSG, a high performance 3D graphics toolkit. To get started with 3D C++ coding, you can take a look at the OSG documentation and learn only as much OpenGL as you need, when you need it.

How do I add an airport?

You can add your airport to the $FG ROOT/Airports/default.apt.gz file, but to get the airport to show up visually, you will have to rebuild the scenery around the airport. The format of the default.apt file is documented at http://www.flightgear.org/Docs/AirNav/AptNavFAQ.FlightGear.html.

Can I generate my own scenery?

1rightarrow.png See TerraGear for the main article about this subject.

Yes, though it can be a difficult task. FlightGear's scenery generation is handled by a sister project, TerraGear.