This page is intended to help you solve the problems in using FlightGear OS X 1.9.0 or later. If you cannot solve your problem by reading this page, Please post a bug report to Bug Tracker. You can also either email us or post a message to Help and Open Discussion. Troubleshooting for 1.0.0 or earlier can be seen Troubleshooting for 1.0.0 or earlier

As troubleshooting is sometimes time-consuming work, we reccomend you go visit Downloads page to get the latest version before starting troubleshooting.

We recommend you give us a bug info with:

  • Machine spec (e.g. Core2Duo MacBook Pro 2.3GHz Mac OS 10.5.8)
  • Possible cause of crash (e,g, When I pressed 'Start flight' button, it went crash).
  • How frequently it happens (reproduceable or not)
  • Non-default options you specified
  • Crash log and/or error messages (GUI Launcher)

FlightGear Mac OS X doesn't launch

When don't launch at all, you need to find a cause of it. You can see some hints using Console. Check if Mac OS wrote some error logs like something is missing or some errors by launching /Applications/Utilities/ Sending us the error log can help you solve the problem.

Possible causes are:

  • Missing library or framework
    You will see messages like the ones below on the
      Library not loaded: @executable_path/../Frameworks/RubyCocoa.framework
      Referenced from: /Applications/
      Reason: image not found
    In this case, the error log shows that RubyCocoa.framework is missing or broken. You need either reinstall or place RubyCocoa.framework to /Applications/ manually.
  • Trying to launch FlightGear on Mac OS 10.3.x or earlier
    You can run FlightGear (since 0.9.10) on Mac OS X 10.4 or later.
  • You update the launcher from svn repository?
    The runtime error could occur when you update the launcher with the latest files in the svn repository. This happens because deleted files from svn repository can be still at the "Resources" folder. In this case, run the following command from (/Applications/Utilities/
    $ rm /Applications/*.rb
    Then, update the launcher again. For detailed information about updating the launcher, go visit How to update the launcher.

I cannot select an aircraft and an airport

This happens when either the launcher cannot find the data folder or some data are missing in the data folder. The typical problem on this issue is that the launcher does come up but no aircraft is shown on Aircraft tab. Check the following items to solve the problem.

  1. Did you install a proper package?
    You should install one of the following packages depending on your situation. For 2.0.0, you can download FlightGear-2.0.0.dmg from Downloads page.
  1. Does the path to FlightGear contains spaces?
    It is reported that this problem occurs when the path to FlightGear contains spaces. Please move or rename the FlightGear folder so that the path to FlightGear doesn't have any spaces. (You don't have to rename 'Machintoch HD'. It has nothing to do with this issue). The newer version (r115 or later) in the svn repository can avoid this problem. FlightGear 1.0.0 doesn't have this issue.
  1. Did you try re-installing FlightGear Mac OS X?
    When your disk is almost full (or some other reasons), Installation of FlightGear Mac OS X might not be able to copy all data to the Applications folder (the full package is more than 250MB). Delete or back up some other data, and then, reinstall FlightGear Mac OS X. If this doesn't help, download the full package again and re-install it. Don't forget to trash the before you re-install it.
  2. Is the icon of shown properly?
    If the icon of is shown as a default Application icon (Pen, brush, and ruler on two sheets), FlightGear is not installed properly. Re-install by copying it from the dmg file.
  3. Do you have older FlightGear Mac OS X?
    An older (of broken) preference file of FlightGear Mac OS X could cause this problem. Move it by the command below:
    $ mv ~/Library/Preferences/net.sourceforge.macflightgear.plist /tmp
    Relaunching FlightGear Mac OS could let you open the pop-up buttons.
  4. Did you try restarting your Mac?
    It is possible that an unstable system state can cause this issue. If you see no error messages in but it still happens, try restarting your Mac. It could solve this issue
  5. Did you update the launcher to the latest one?
    The latest version of the launcher may help your problem. Go visit Downloads and get the latest launcher.

If none of above solves your problem, either email me the error message written to (/Applications/Utilities/ or post it to Help and Discussion forum.

FlightGear closes when I press "start flight"

  1. Did you install a proper package?
    You should install one of the following packages depending on your situation
    • FlightGear-0.9.10.dmg - Full package for everyone
    • FlightGear-0.9.10-updater.dmg - Updater for 0.9.10 pre releases, not for 0.9.9 or earlier version.
  2. Do you have the data folder?
    You can check this by running the following command from
    $ ls /Applications/
    If you don't have the data folder, you need to reinstall the full package.
  3. Are there any options specified at the "Others" tab at the launcher window?
    Some command-line options can crash FlightGear. Wrong command-line options also fails launching FlightGear. You can check the (error) messages from Console (/Applications/Utilities/ Specifying --help also makes FlightGear quit immediately after writing help messages to Console.
  4. Is there an iconified window named "fgfs" on the Dock?
    If FlightGear is launched with iconified, it may go crash. You need to click the iconified window on the dock, and then, open preferences from the menu bar of the main window (not the GUI launcher) to uncheck "Default Iconic WIndows"
  5. Did you specify a call sign with spaces?
    FlightGear does not accept a call sign with spaces. FlightGear exits immediately after you launch it due to this issue. This is not a 'crash' but an error (Inappropriate, though). Use '_' instead of a space.
  6. Can you launch FlightGear from
    Try the following command from Terminal (/Applications/Utilities/
    $ cd /Applications/
    $ ./fgfs --fg-root=./ --aircraft=p51 --airport=KSFO
    If you can launch FlightGear successfully, then there is some problem in launching FlightGear from the launcher. Please send us the error messages written to Console

GUI launcher crashes when I press "Install Add-on Data" on "Others" tab (1.0.0)

It's a bug in a ruby script (Others.rb). I've confirmed the crash on pressing "install add-on data" button on my Mac. There is an updated file so you can download it from Downloads page. You can also download a single fixed file:

Clicking the "download" link next to Revision 150 will get the file, and then, copy it to /Applications/ by using Terminal.

If you are not familiar with Terminal or unix command tools, then use Finder to open the contents of Applications/FlightGear by Ctrl-clicking the FlightGear icon and choosing "Show Package Contents." This allows you to browse inside the FlightGear folder.

I don't know what option is for what

  1. Open the Advanced Features and press View Options at the Others tab
    A browser window comes up and shows the brief help message.
  2. Read Users Guide
  3. Read The FlightGear Manual

FlightGear (Simulator - a.k.a. fgfs)

FlightGear crashes at the splash screen

  1. Did you select an unstable aircraft?
    Some aircraft are under construction and may not be stable yet. Try some other aircraft (like c172p, p51d or A6M2) to check if FlightGear works with it. If so, stop using the aircraft that crashes FlightGear.
  2. Did you change preferences from the menu bar of FlightGear? If you changed any preferences on 1.0.0 or earlier, try the command below:
    $ mv ~/Library/Preferences/ /tmp
    Then restart to see if it works properly.
  3. Do you see "unknown exception" message on a log (2.0.0) ? If you see this message in a log, this is a Mac specific bug on 2.0.0. Be patient I'm fixing on this issue. You can try my quick fix available here>. You can install this by:
  4. unzip
  5. Open data folder using Advanced Features >> Others >> open data folder
  6. Go up to Resources folder (Resources folder is a parent folder of data folder).
  7. replace fgfs with the fresh one by copying fgfs into Resources folder.

FYI, you can open the log via Advanced Features >> General >> view log on the GUI Launcher.

See also: FlightGear closes when I press "start flight"

FlightGear crashes while I'm flying

It is reported at the flightgear-devel mailing list that sometimes ATC might crash FlightGear 0.9.10. It happens when ATC is updating its status. Probably it cannot get the proper coordination of an aircraft at a certain condition. Disabling it may solve this problem. (0.9.10)

See also: FlightGear crashes at the splash screen Note: This doesn't happen on 1.0.0

FlightGear crashes when I quit it

It is noticed that sometimes multi-player mode can crash FlightGear during its clean-up process. This problem is under investigation. It's not that harmful after all so be patient please. (0.9.x) Note: This doesn't happen on 1.0.0

I can't find keys to manipulate aircraft

  1. Read Jump Start Guide
  2. Read FlightGear Short Reference

Some keys don't work

Since Mac OS X assigns some function keys to hardware manipulations, these keys are not available on FlightGear. In this case, you can try option + function keys. (e.g. you can hide GUI by pressing option-F10. It works at least on my MacBook Pro with Leopard) You can also read Hacks to change key bindings. If you are using a notebook Mac like MacBook Pro or PowerBook, key pads are not available unless you press F6 (num lock). This is not a very good way because enabling num lock disables some other keys. Probably you should change key bindings. Please read Hacks.

FlightGear runs very slow

The performance of FlightGear highly depends on machine specs, especially on CPU and GPU power. We recommend you use Power Mac, MacBook Pro, or Mac Pro. However, there are some means of improving the performance.

  • Disable Textures at the launcher window.
  • Disable all rendering options from the View menu on the fgfs window.
  • Decrease LOD ranges (Detailed=500, Rough=1000, Bare=10000 or less)
  • Remove or rename /Applications/ folder
  • Select smaller window size
  • Select faster or disable fogs at the launcher window.
  • Disable Random objects at the launcher (or specify --disable-random-objects manually)
  • Decrease visibility by specifying --visibility=<distance> in meter.
  • Disable ATC from the ATC/AI menu on the FlightGear window
  • Disable Download scenery on the fly at the launcher
  • Fly as high as you can
  • Fly over the ocean
  • Disable Sound and ATC chatter (from either launcher or File menu on the fgfs window)
  • Close all other applications that runs on your Mac
  • Connect the power cord to your Mac.
  • Choose 'Better Performance' from the Battery icon on the Mac's menu bar.

See Improving Framerates> available at flightgear wiki page for more detail.

Scenery Downloader (terrasync)

I can't download scenery

Make sure these things are all true;

  1. Did you check Download scenery on the fly option at the launcher?
    You need to enable this option at the launcher window.
  2. Did you launch from Applications folder or other writable folder?
    Launching it from mounted disk drive does not allow terrasync to add scenery to the data folder.
  3. Do you run no other terrasync?
    Running another terrasync causes this problem. please check this by running the following command:
    $ ps auxwww | grep terrasync
    If you find any terrasync running on your Mac. kill the process by:
    $ killall -KILL terrasync

I'm in the middle of the ocean even though I check "Download scenery on the fly."

First of all, we recommend you update the launcher to the latest version. The one comes with 0.9.10 doesn't specify the runway by default, which means you need to designate a runway for a selected airport from 'Others' tab. If the log file complains that it cannot find a runway 28R or something like that, that must be it. The latest launcher (r144 at the time of writing this) specifies the default runway so this problem doesn't happen.

However, sometimes this problem happens even your Mac is connected to the network, especially when you specify an airport for the first time. You can restart FlightGear and choose the same airport. This time, you can see the scenery objects. This problem occurs if the server is down for some reason. You need to wait for a while in this case. Needless to say, you will be in the middle of the ocean if your Mac cannot access the network.

I can't use the old downloaded scenery data when I upgrade FlightGear.

If you upgrade FlightGear by overwriting the old one, then there's no clue. the scenery data is actually removed by OS. You can still download scenery data, so don't cry.

If you upgrade it by copying the new FlightGear to some different folder other than the old one, you're lucky. There are two options you can do to get the downloaded scenery data back to the new FlightGear.

  1. Copy downloaded Scenery folder into the new FlightGear folder.
    • Use either Finder or Terminal to go to /Applications/<old-FlightGear folder name>/
    • Copy or move Scenery-Terrasync folder to the data folder inside the new FlightGear folder (same hierarchy as the old one)
  2. Add the following option to command-line options box on "Advanced Features" > "Others"
    • --fg-scenery=./data/Scenery:./data/Scenery-TerraSync:/Applications/<old FlightGear folder name> Note: Don't forget to copy the Scenery-Terrasync folder when you erase the old one.

11 Responses to “Troubleshooting”

  1. raymond Says:
    I don't understand how i can use flight gear with decent framerates on my 800mhz G4 and can't get it to get above 1 to 2 frames per second on my 2.0 ghz intel macbook. what's the deal?
  2. Tat Says:
    I recommend you disable textures on G4 machines. 0.9.10 is a bit optimized compared to 0.9.10-pre releases so give it a try. Please take a look at "FlightGear runs very slow" and try some of these. As far as I've experienced, PowerBook G4 1GHz can run FlightGear Mac OS X 0.9.10 up to 45fps with --disable-textures option.
  3. Tat Says:

    To Bryan: Thank you for your feedback but I had to delete the log you posted because it's too long. I saved the log so could you email me what was you doing when it went crash? It looks like fgfs went crash at its very early stage but I'm not pretty sure only with the given info. Thank you.

  4. Udit Says:
    I downloaded the file from the Apple website and installed it. On clicking the icon, the launcher window does show up but I can't select any a/c or airport as the scroll-down windows won't open! Could someone please help me with this? Thanks!
  5. Geoff Lee Says:
    I downloaded the latest version from the Apple site today 2nd Jan 2007. I have a Power Mac Blue and WHite G3/400 MHZ with 576 Mb RAM approx. Running Mac OS 10.4.8 no worries. Whn I launch Flight Gear I get the initiaql window (the START WINDOW) no worries. I left it at the default aircraft C172 and the default airfield and download scenery on the fly. It goes OK to what I assume is the MAIN WINDOW and it says it is: 1. Reading airport and navigation data then 2. Loading aircraft then 3. Initialising subsystems 4. Then bang it quickly flashes back to the START WINDOW briefly then a window pops up: 5. The Application FlightGear crashed unexpectedly. Mac OS and other apps are not affected. Click to reopen the App again. Click Report to see more details or send a report to Apple. I have FlightGear in Applications on the Hard Disk. I have tried different aircraft and locations and disabled download scenery on the fly but the same sequence leading to the crash occur. I cannot find anything in discussions of problems that describes this particualr crash. Cheers Geoff Lee City: Melbourne Country: Australia
  6. Jorge Says:
    Hi ! I have some crushes after a while loading any aircraft, be it stable or not. Also I was reading that you have to install the RubyCocoa framework to allow flying FG. But this site have only for MacOSX 10.4.8 or later version of this software. Does anybody know where to find a RubyCocoa version for preview versions of MacOSX ??? I run a DuoCore Intel 2.8 GHz - 1GB RAM - OSX86 Thank you for any help! :) Jorge Argentina
  7. Tat Says:
    Jorge, If you are talking about Mac OS X 10.5 preview version, I don't recommend you run FlightGear on it. If not, FlightGear OS X already has RubyCocoa.framework so you don't have to install RubyCocoa. I don't get what causes the crushes so why don't you send me the crush logs. it's in ~/Library/Logs/CrashReporter/fgfs.crash.log
  8. Chris Says:
    Can anyone tell me about ways to download extra scenery for Macs? the main FG website only refers to PCs.
  9. Tat Says:

    Simply checking "download scenery on the fly" will download scenery for you, though it won't show up until it is downloaded. If you want to download some scenery files, then visit this site. If the graphical interface doesn't work, then try ftp.

    When you complete download, press 'Install Add-on Data' button at the "Others" tab in the launcher's Advanced Features. See Users Guide for more info on this.

  10. rpg Says:
    Hi, this is a great sim. However, I can't seem to click on the instruments to activate them in all cases. This is annoying because it means I can't start the Lightning. . . OS 10.4.9 on a dual core Intel iMac. Thanks for any help.
  11. Mike Stranger Says:
    Thanks 123 adware