@GG1 4877 posted:Northern Pacific has not been an entity since 1970. The name is likely in the public domain regardless.
A business name is a trademark. Trademark protection can be continued indefinitely, as long as it's being used in some way as it was originally used (i.e. with respect to something involving a railroad), as long as it's renewed every 10 years.
Regardless, another business can use someone else's trademarked name if that use is not confusingly similar (in the mind of the public) to original business's use of the name. Presumably, it has been determined that use of the name Northern Pacific with respect to an airline is not confusingly similar to its use as the name of a railroad. Therefore, the use of the name Northern Pacific for an airline would be allowed.
