FlightGear is a free, open source multi-platform flight simulator. The goal of the FlightGear project is to create a sophisticated and open flight simulator framework for use in research or academic environments, pilot training, as an industry engineering tool, for DIY-ers to pursue their favorite interesting flight simulation idea, and last but certainly not least as a fun, realistic, and challenging desktop flight simulator.
If you want to try this simulator on Ubuntu Linux and its derivatives. You can use the PPA repository which supports Ubuntu 13.10 Saucy, Ubuntu 13.04 Raring, Ubuntu 12.10 Quantal, Ubuntu 12.04 Precise.
To get started, press Ctrl+Alt+T key combination on your keyboard to open terminal. When it opens, run the command to add the PPA:
sudo add-apt-repository -y ppa:saiarcot895/flightgear
Then update package lists on your system:
sudo apt-get update
Finally install it via following command:
sudo apt-get install flightgear