Currently the site holds 4,198 airlines in 22 worlds. These airlines fly a total of 4,424,851 flights.
To view the map of an airline first select the world. You can then select one of the airlines that have already been imported. Optionally you can select the size of the airport. Selecting a number will only show airports that are equal or bigger than your selection.
If you want to see two airlines at the same time, use the following form and choose from two airlines within the same world.