Merging into one airline may take up to two years, the Star Tribune in Minneapolis reported Monday.

The airlines first plan to have customers for each carrier check in at the same airport counter. Northwest employees will not put on Delta uniforms until next year, however, and Northwest planes will not begin to fly Delta routes until next summer, the newspaper said.

"Employees and customers need to be our primary focus," said Steve Gorman, Delta's chief operating officer.

While the companies merge, board room directives will be tested to see their effects on customers and employees, he said. The decisions from the top will be not stop at "table top paper exercises," he said.

"At the end of the day, this new airline will be about unparalleled service of a superior nature to our competition," said Ed Bastian, Delta's president and Northwest's new chief executive officer.

Northwest will be run as a subsidiary until the Federal Aviation Administration approves of a merger of flight operations. That approval could take up to 18 months, the newspaper said.