SEPTEMBER 14, 2007. Northwest Airlines has signed a codeshare agreement with Midwest Airlines for tickets purchased beginning Nov. 3 with travel starting on Nov. 17, 2007.

The first phase of the codeshare agreement will include Northwest's Hawaii-bound flights from Seattle, San Francisco and Los Angeles with travel beginning on Midwest Airlines in Milwaukee, Omaha and Kansas City.

The Northwest-operated flights will also be identified in reservations systems and airport flight displays by the Midwest Airlines two-letter "YX" code.

"This is just the first step in expanding the networks of both carriers by opening up 250 city-pairs and more than a 1,000 new flight options for customers," said Nathaniel Pieper, Northwest's vice president - alliances. "Codesharing allows Northwest to offer our customers the expanded reach of two airlines while enjoying the convenience of a single ticket and check-in."

The new codeshare agreement augments the initial Northwest and Midwest partnership, started in May 2006, when the carriers forged a frequent flyer program, and formalizes the Memorandum of Understanding the two carriers signed in May 2007.

Members of Northwest's WorldPerks and Midwest's Midwest Miles frequent flyer programs will continue to receive accrual and redemption benefits on flights operated by both airlines.