United Airlines ( UAUA) has tentatively won the right to operate a route between Washington's Dulles International Airport and Beijing starting March 25. The Transportation Department said Tuesday that it has made a preliminary decision to award seven weekly flights to United under the 2004 U.S.-China aviation agreement, which allowed 195 new weekly flights over six years. Four U.S. airlines had applied to begin China routes in 2007. "It's not every day we get the opportunity to make flying more convenient, support airlines and boost the economy by proposing to make it easier to fly between the world's two most dynamic economies," said Transportation Secretary Mary E. Peters in a prepared statement. The DOT found that United's proposal could benefit the greatest number of passengers. More people travel to China from the Washington metro area than from any other U.S. city that currently doesn't have nonstop service, it said. Also, United offered 253,000 seats annually, more than any other carrier. Interested parties have 14 days to file objections. American ( AMR) had sought to fly between Dallas and Beijing. Continental ( CAL) applied for Newark to Shanghai, while Northwest ( NWACQ) sought Detroit to Shanghai. Last month, American sought to change its proposal by adding a Chicago hop on the westbound flight. The DOT denied American's motion, saying any amendment this late in the proceeding would significantly delay the start of new service.