Northwest Airlines has introduced the newest and largest airplane in commercial aviation, a super-modified, more effricient version of the Boeing 747 that will enable the airline to fly not-stop between U.S. and Asian markets.

Northwest is the world's first carrier to take ownership of the 747-400, which can carry 420 people for more than 7,500 miles without refueling. The model 400 is valued at about $125 million.The plane originally was scheduled for delivery in December, but production problems at Boeing caused a delay.

The model 400, with its increased capacity for passengers and freight, will be used by Northwest exclusively in the highly competitive and highly lucrative Pacific area. Northwest has ordered 10 of the planes and will obtain six this year.

The model 400 made its first public appearance Tuesday at Minneapolis-St. Paul International Airport, where it was boarded by 25 company executives and officials of the Federal Aviation Administration for a three-day around-the-world proving flight to New York, Tokyo, Los Angeles and Detroit.

With an extended second-deck hump and distinctive upward-angled wing tips, the 747-400 is a larger, but sleeker version of the long-haul passenger plane that make aviation history when it was introduced 20 years ago.

There are four galleys to serve passengers, larger storage compartments for carry-on baggage and a hideaway bunk area for use by the 16-member crew of flight attendants on the 13- to 14- hour trips.

Its high-tech cockpit features computerized read-out screens and contains 600 fewer dials, switches and gauges than older 747s. The new technlolgy enables the size of the flight crew to be reduced from three pilots to two.

"It's very easy to fly. It's very light on the controls," said Capt. James Hancock, a Northwest pilot who has been test-flying the model 400 since June.

In designing the interior, Northewest increased the number of executive-class seats to meet the demand of business passengers who want better seating than coach class but don't want to pay first-class fares. The new planes have 106 executive-class seats, compared with 50 to 80 on older 747's

The 747-400 will begin carrying commercial passengers next week on flights between the Minneapolis-St. Paul and Phoenix. Northwest officials chose to use the plane on a domestic route for two months to give a number of pilots the opportunity to fly the plane.

In April the plane will begin regular non-stop service between New York and Tokyo, a flight of more than 13 hours and 6,700 miles.

A second 747-400, scheduled for delivery at the end of the month, will be used for the Seattle-to-Hong Kong route.

Northwest also intends to initiate additonal non-stop flights this summer, including the Twin Cities-Tokyo, Detroit-Seoul and Los Angeles-Osaka routes. The airline is seeking government approval for routes to Sydney, Australia, and singapore.

The new 747s will enable Northwest to redeploy its smaller 747s on shorter trans-Atlantic and Pacific routes.