The business expansion plans of Northwest Airlines tied to the opening of a new runway at Narita airport and a new terminal at Detroit Metropolitan Airport have been largely unaffected by the Sept. 11 attacks, according to a Tokyo-based executive of the airline.

Unlike many other foreign airlines operating in Japan, which slashed their flight operations in the wake of the attacks, Northwest has pursued a relatively aggressive policy in the Asia-Pacific region, keeping its timetable of trans-Pacific flights virtually intact.

"We think it will be easier for us to bring our business back" when flight demand recovers, said Perry A. Cantarutti, the airline's director of marketing and distribution planning for the Asia-Pacific region.