Flight Gear is a free and highly sophisticated flight simulator.

Packages are available for the following releases:
Ubuntu 13.10: 3.0.0-1~getdeb2~saucy
Ubuntu 13.04: 2.12.0-1~getdeb2~raring
Ubuntu 12.04: 3.0.0-1~getdeb1
Ubuntu 12.10: 2.10.0-1~getdeb1

Package downloads per version:
Version 2.10.0: 6119
Version 2.12.0: 2662
Version 3.0.0: 2777

Uninstall the application with the following command:
sudo apt-get remove flightgear