Which airline was the first to operate the Boeing 747-400 commercially in 1989?

Northwest Airlines was the first airline to operate the Boeing 747-400 commercially in 1989.

Northwest Airlines introduced the Boeing 747-400 into passenger service in 1989. The improved jumbo jet featured a two-person glass cockpit, winglets and greater range than earlier 747 versions. These changes made it especially useful for long-haul international routes.

The 747-400 retained the distinctive upper-deck shape of the original 747 but incorporated substantially modernized systems. Its cockpit no longer required a dedicated flight engineer, because electronic displays and automation replaced many earlier instruments and controls.

The aircraft became one of the most successful 747 variants and was operated by major carriers around the world. A frequent confusion is with Boeing's 747-8 Intercontinental, which is a later and substantially redesigned version. Northwest eventually became part of Delta Air Lines in 2010, but its 747-400 launch role belongs to the earlier airline.