The biggest airplane in Northwest Airlines' fleet -- a Boeing 747-400 -- will be the first aircraft to be painted in the red-white-and-blue color scheme of Delta Air Lines, which acquired Northwest last week.

Getting the right airplane on the right route is one of the bedrock elements of the Delta-Northwest merger, which will create the world's largest airline.

Delta executives did not disclose the routes that will be affected by the fleet changes. But Glen Hauenstein, a Delta executive vice president, said the ability to move planes to where they are needed is the "key driver" in reaching the merger's financial goals. Delta executives have said they expect the combination will yield about $1 billion in annual cost savings and $1 billion in new revenue.

"Northwest wide-body planes are probably too big for the markets they serve," said Hauenstein. The 747, which seats 403 passengers, is one of Northwest's twin-aisle or "wide-body planes" and it is expected to be flown on some of Delta's routes next year. One possibility is operating 747s on an Atlanta-Tokyo route. Delta's largest hub is in Atlanta, while Northwest has a major hub in Tokyo.

"It will take some time to migrate the brand," Delta CEO Richard Anderson said in an interview. But he added that Northwest customers will begin to see changes in the coming months, such as the addition of blue leather seats on Northwest planes and the appearance of Delta's food offerings on Northwest flights.

But Anderson and his management team are particularly intent on achieving the financial benefits that they believe will be produced by blending the fleets of Delta and Northwest. Hauenstein said that Delta's largely Boeing fleet is heavily weighted toward large single-aisle planes and small twin-aisle planes. In contrast, he said, Northwest's Boeing and Airbus fleet is dominated by small single-aisle planes and big twin-aisle jets. When you merge the fleets you get "planes as small as 100 seats and as big as 400 seats and pretty much everything in between," he said.

For some time, Hauenstein said, the airline industry viewed fleet simplification as a smart business choice, because having a small number of plane types can reduce maintenance and pilot training costs.

But he argues that standardization comes at a high price.

"It also drives a lot of revenue inefficiencies in that you can't tailor capacity to demand," he said. Instead, Delta is striving for a flexible fleet.

The first 747 will get its makeover in Victorville, Calif., and reenter service Dec. 12, Anthony Black, a Delta spokesman, said Friday. Northwest's entire fleet is set to be repainted in Delta's color scheme within two years.

By summer 2009, the first 20 to 30 airplanes from the Delta and Northwest fleets will be swapped, said Hauenstein, who oversees network planning and revenue management at Delta. If a Northwest 747 is moved onto a Delta route, a Delta 777 might be substituted in its place. A Delta 777 is configured with 268 to 276 seats.

Hauenstein said that Delta plans to phase in more plane swaps after the summer season, but it is moving cautiously because management wants to provide a smooth transition for customers.

Northwest and Delta have only one plane type in common, the single-aisle Boeing 757.

Together, but still separate

Delta and Northwest pilots started working on a combined labor contract Oct. 30. But the Federal Aviation Administration is not expected to permit Delta and Northwest to combine their flight operations until late 2009 or early 2010. However, the new Delta can move ahead to redeploy its planes on a combined route network.

Until the merger is completed, Northwest pilots and flight attendants will continue to fly on the Northwest aircraft that are shifted to some Delta routes. The reverse is true of Delta pilots who'll be operating Delta planes on Northwest routes.

Delta plans to place Northwest planes on some Delta routes before labor union representation issues are resolved. But Steve Gorman, Delta's chief operating officer, said Delta will honor Northwest's labor contracts during this transition period.

Consequently, he said, Northwest's unionized flight attendants will keep working on Northwest planes.

If a Northwest plane flies on a Delta route, Northwest ground workers will serve that flight if the plane lands at an airport where Northwest workers are employed. Northwest's airport workers are represented by the International Association of Machinists and Aerospace Workers. Delta's flight attendants and ground workers are not union members.

Since the merger deal was consummated Oct. 29, Delta and Northwest executives have been moving quickly to add their codes to each other's flights. By blending both route networks, the new Delta will offer flights to more than 375 worldwide cities in 66 countries. Northwest brought its joint venture partner, KLM, to the merger, while Delta has a similar business arrangement with Air France.

Hauenstein said the merger and Air France linkage will generate more passengers for the Twin Cities-Paris route.

In June, Northwest announced that it would suspend daily service to Paris from Oct. 1 through late March of next year. High fuel prices hurt demand for the flight, which was launched in April.

Hauenstein envisions a brighter future for the route because of the passengers who'll flow through the Air France and KLM hubs. He said, "I would be shocked if we weren't able to make [the Twin Cities-Paris route] work year-round."

Liz Fedor • 612-673-7709