The good news: An airline fare war is heating up at Dulles. The bad news: You have to go to Milwaukee to take advantage of it.

Midwest Express Airlines Inc., an all-first-class airline that caters to business travelers, announced yesterday that it will begin service between Milwaukee and Washington Dulles International Airport on Sept. 1, with two flights in each direction daily.

The Milwaukee-based airline's move comes less than two months after US Airways MetroJet said it would begin new service from Dulles, including two daily round-trip flights between Dulles and Milwaukee.

Midwest Express didn't announce its fares yesterday, but company officials said they would be competitive with MetroJet fares. MetroJet's service, which starts Sept. 9, will cost $79 one-way for advance-purchase tickets and $159 one-way for tickets purchased the day of the flight.

Lisa Bauer, vice president for sales and distribution, said earlier this week that Midwest Express is prepared to take on low-fare competitors at whatever fare they charge. "We'll be whatever fare they're at," she said.

Bauer said Midwest has taken on low-fare carriers in the past, notably Continental Lite and Vanguard -- and ultimately both upstarts left the Milwaukee market.

Midwest, which flies in a handful of markets, is clearly counting on its reputation for good service and all first-class seating to beat back the threat from MetroJet in its hometown. US Airways Group Inc., based in Arlington, is the sixth-largest airline in the United States, and MetroJet is a brand that it uses for lower-cost flights in smaller markets.

Bauer, who noted that MetroJet flies 737 jetliners with three-abreast seating and minimal food service, sniffed: "Are you going to ride on La-Z-Boys and eat lobster or fly MetroJet?"

In response, US Airways spokesman Richard Weintraub said: "We are certainly proud of our low-fare MetroJet service, and the 13 cities that it is now scheduled to serve from Dulles Airport."

Travelers on MetroJet will be able to change their reservations without the standard $75 change fee, another US Airways spokesman pointed out. Midwest Express charges $50 for such changes. Travelers on MetroJet will be able to accrue frequent-flier miles in the US Airways program for domestic or international travel or will be able to earn a free MetroJet ticket for every eight round trips or 16 one-way trips on MetroJet.

Midwest Express passengers can earn miles in that airline's frequent-flier program for use on either Midwest Express or Northwest Airlines or for international flights on Virgin Atlantic and Air New Zealand.