An increase in the number of direct flights between China and the United States means there are more opportunities to develop service, according to an official with one of America's major international airlines.

"With Beijing and Shanghai already served, we are looking at other emerging markets in China," Andy Buchanan, managing director of international planning for United Continental Holdings Inc (United) wrote in an e-mail to China Daily. "Given our long history of Asia Pacific service and the strength of our San Francisco hub, we are always evaluating opportunities to profitably expand service."

Because air travel between the US and China has become increasingly profitable, a number of US and China-based airlines have increased or will increase flights.

In June, Chicago-based United will begin nonstop service between San Francisco and Chengdu, a Chinese city with a population that exceeds 14 million people.

"Our growing fleet of modern and fuel-efficient Boeing 787 aircraft makes a number of Chinese markets outside of Beijing, Shanghai and Hong Kong more attractive. Chengdu is one of those markets," wrote Buchanan.

A merger of the AMR Corp - which was the parent company of American Airlines - and US Airways Group Inc on Dec 9 established American Airlines Group Inc (American) as the largest air carrier in the US.

Brian Foley, president of Brian Foley Associates, an aviation advisory firm based in Sparta, New Jersey, said American should look to generate more opportunities for business between China and the US.

"To remain competitive with United and offer customers comparable worldwide service, American-USAir will have to develop the US/China route," Foley said in an e-mail to China Daily.

American now offers Beijing to Chicago, Beijing to Los Angeles and Shanghai to Los Angeles trips, and plans for new routes are in the works, possibly including Dallas/Fort Worth International Airport. American Airlines' headquarters is in Fort Worth.

"As American's primary hub, Dallas would clearly be an early candidate," Foley said. "China Southern already goes to Detroit, but no one is currently offering nonstop to Washington, DC's, Dulles International Airport."

American Airlines declined to comment for this story.

Hainan Airlines, the fourth-largest airlines company in China, has made several successful overtures to expand its business in the US.

Earlier this year Hainan Airlines doubled its direct flight service between Beijing and Chicago, pushing the number of weekly flights to four.

In December, it also secured federal approval for nonstop service to and from Boston's Logan International Airport. Until recently, Boston was the largest US airline market without nonstop service to China. According to a filing with the US Department of Transportation, Hainan Airlines expects to serve close to 5,000 travelers a month and should begin flying from Boston to Beijing as early as June 2014.

John Nance, an aviation analyst for ABC News and Good Morning America, points to issues of transparency as a key component of the developments in the airline industry.

"Aviation is first of all a planetary public utility and not many people want to realize that," Nance said Tuesday in an interview with China Daily. "As these upticks in service gain speed, it's not just a matter of convenience. It also has to do with the breakdown of cultural barriers, the immediacy of economic traffic and the increase in the understanding of the people in both places."

"To stabilize the world, this is a very good thing," Nance added. "My definition of a public utility is an enterprise of such incredibly high value to a society that it cannot be left to the vicissitudes of the open market. Aviation is probably becoming the first worldwide public utility."

According to the Office of Travel and Tourism Industries (OTTI), China accounted for almost 1.5 million visitors to the US in 2012. A 35 percent increase in Chinese visitor volume was the largest percentage among the top 10 international visitation markets.

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