Can I make an airline named after an airline that does not operate anymore? Ex Midwest
Preferrably not. But if you can be sure that the name is not owned by anyone anymore then there is no problem.
So if the code and name is retired then im good?
Indeed, as long as noone owns the rights to the name. PanAm springs to mind, as the name and brand are still owned intellectual property rights...
Many airline names we think of as defunct actually still are in use. For example, US Airways operates commuter flights under the names of most if not all of its predecessor companies. You don't hear about the name frequently, but the trademark is still owned and in use. And like soarinternational mentioned, PanAm is now a railroad. I would just steer clear.