By Christian Plumb

NEW YORK, Mar 29 (Reuters) After a 14-year wait to get into the world's most populous country, American Airlines is understandably eager to start flying from Chicago to Shanghai.

AMR Corp.'s American Airlines, which set up a Beijing office more than a decade ago in a bid to build relationships, on Sunday is scheduled to start flying up to 245 passengers a day to the fast-growing US trading partner.

American expects to fill an average of 86 per cent of available seats on its Chicago-to-Shanghai flights, a load factor that should allow it to turn a healthy profit on the route.

''China is the last and most important aviation global market,'' said Julius Maldutis, head of consulting firm Aviation Dynamics.

But the glass remains half empty for American and other US carriers that have been granted limited access to the lucrative Chinese market.

Limited flying rights available starting in 2007 will be fiercely contested by rivals like Continental Airlines and UAL Corp.'s United Airlines.

Profitable international routes are crucial to U.S. carriers' efforts to climb back to profitability after years of surging fuel costs and increased competition from low-cost carriers on domestic routes knocked them deeply into the red.

The US and China are set to hold aviation market liberalization talks next month, and US airlines will be there to press their case for allowing more flights, sooner.

'THE PRESSURE IS HUGE' ''There's keen industry interest, that's for sure,'' said a US government official familiar with the talks, to be held in Beijing April 19 and 20.

But Chinese carriers, who have billions of dollars in jets on order from Boeing Co. and European archrival Airbus, are just as intent on keeping the status quo.

A well-informed source at China Eastern Airlines Corp. Ltd. told Reuters that the country's top three carriers have sent letters to the General administration of Civil Aviation of China (CAAC) strongly opposing the open skies scheme advocated by their American counterparts.

''We have to do so. If they open up the skies, we are dead,'' he said. ''American airlines are coming in one after the other, the pressure is huge already as it is.'' Other Chinese airlines declined to comment.

American Airlines, which has a partnership with China Eastern, sees it differently.

''The market is growing fast enough to support additional service from both sides,'' Henry Joyner, American's senior vice president for planning, said in an interview.

American Airlines estimates that annual passenger traffic between the superpowers, already at about 3 million, is growing by 500,000 passengers, or about 17 per cent, a year, bolstered by business traffic and Chinese-Americans making home visits.

For now, it plans to compete ''aggressively'' for the rights to open additional routes in 2007, Joyner said.

FIRST CHANCE The quest for more routes may pit AMR against Continental, which started flying between Newark, New Jersey, and Beijing in June and wants permission for a Newark-to-Shanghai route.

Determined not to be eclipsed by American and Continental, US-China veteran UAL recently met with Chinese officials as it seeks to open additional routes to Beijing, Shanghai and Guangzhou, its chief executive told the airline's employees in a recent message.

The US airlines' first chance for more such flights will be in late March 2007. The Department of Transportation is due to award 14 passenger frequencies-- or daily round trips -- for an existing US-China carrier.

Those rights, seven of which are restricted to a group of smaller cities, are being awarded under a 2004 pact. The agreement also allows the DOT to cleara new carrier to start flying in 2008. Delta Air Lines Inc, now in bankruptcy, will make another try for a China route from Atlanta after losing a previous competition and is ''pretty confident'' that it will get it, said Sametta Barnett, Delta's director for government affairs in Washington.

REUTERS SY BST1925