I am flying between Hamburg and the US since 1991. When I started, Delta had a connection Hamburg – Atlanta. The plane was often quite empty, finally the connection was discontinued.

Since 2005 CO (UA) is flying Hamburg – Newark and I have been on it from day one.

For a while Emirates was also flying Hamburg – New York (forgot what Airport), but that was also discontinued.

So, my general question is: When is a route profitable?

Of cause it’s nice for me as a PAX when the plane is empty, upgrades go through or I can sleep in an empty exit row.

But at what point would an airline start losing money and eventually pull the trigger?