I just dumped and shared pristine disk images and 300dpi scans of the "Sound, Graphics & Aircraft Upgrade" for Microsoft's Flight Simulator 4.0 for MS-DOS. Both 3.5 and 5.25 inch diskettes are now avaiable on the Internet Archive:

720K, 3.5 inch: archive.org/details/fltsim4_so
1.2MB, 5.25 inch: archive.org/details/fltsim4_so

Have fun! ๐Ÿ˜ƒ

Flight Simulator 4.0 - Sound, Graphics & Aircraft Upgrade - 3.5 inch disketteFlight Simulator 4.0 - Sound, Graphics & Aircraft Upgrade - 5.25 inch disketteMicrosoft's Flight Simulator 4.0 upgraded to 800 x 600 pixels VGA graphics.Microsoft's Flight Simulator 4.0 upgraded to 800 x 600 pixels VGA graphics.
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