Which airline operated the first regular commercial service with the Boeing 747-400?

Northwest Airlines operated the first regular commercial service with the Boeing 747-400.

The airline introduced the 747-400 on a scheduled passenger route in 1989. The improved 747 variant featured a two-person flight deck, extended winglets, greater range, and updated systems compared with earlier 747 models.

Northwest was an important Boeing customer and operated a large long-haul network across the Pacific and between North America, Europe, and Asia. Its 747-400 service demonstrated the aircraft’s ability to carry many passengers over intercontinental distances with fewer crew members.

Northwest later merged with Delta Air Lines in 2008. The Boeing 747-400 continued to serve many airlines for decades, although newer twin-engine aircraft eventually replaced most four-engine jumbo jets on long routes.