Airline firms

[fabio guillermo rojas]

Why do airline firms exist?

Seriously, given the unpredictable nature of the airline industry such
as disasters, bad weather, labor strikes and regulation you would
think almost no one could survive in such a wacky business environment.

I know that some firms tend to make profits (like Southwest) but
even in booming times, most airlines seem to live on indefinite
credit lines.

any insight by people in the know?

-fabio