This is a known crash due to an OS problem for X-Plane 9 and OS X.

X-Plane 9 on Mac OS X can crash due to bad text-to-speech voice files. We don’t know why this happens, but sometimes the “Alex” voice that ships with OS X becomes corrupt.

X-Plane has an option to use text-to-speech to speak ATC instructions; when the sim loads, it asks the operating system to load the default text-to-speech voice. If this voice is corrupt, X-Plane will crash.


  • This problem happens on OS X 10.5.6 with X-Plane 8 or 9.
  • This problem will cause a crash during the loading of the sim; you will be able to see the startup screen.
  • An Apple Crash Report will be generated.

To diagnose this problem: open the System Preferences control panel (under the Apple menu) and go to “Speech” tab. If you have a corrupt voice file, the system preferences control panel will crash, just like X-Plane did.


Once you have identified that this is the problem, you can work around it by locating the “Alex” voice pack (a folder called “Alex.SpeechVoice”) – it should be in /System/Library/Speech/Voices/. Delete the voice pack.

To confirm the fix worked, retry the “Speech” tab of the System Preferences control panel.

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