The first flight out of Bejing's new airport will be this Sunday

The brand-new Beijing Daxing International Airport will welcome its first commercial flights this Sunday, September 22, with a double daily service by China Southern to its hub in Guangzhou. That's in advance of the official opening on September 30.

The new airport, whose three-letter code will be PKX, has four runways and plans to handle 72 million passengers each year by 2025, which would make it one of the world's busiest airports.

It won't put the existing Beijing airport, PEK, out of business, though. Beijing Capital International Airport will remain operational. Last year, it saw 100 million passengers pass through its terminals, which made it the second-busiest by passenger numbers after Atlanta. Most airlines will chose to operate to either PKX or PEK, though some intend to use both.

So why the need for such an enormous second airport? Beijing Capital is almost at capacity, which limits growth in such a booming travel market. The designers of Beijing Daxing have chosen a "starfish" design and promise that no passengers will have to walk more than 650 yards from security to gate, unlike the mammoth new Istanbul Airpot (IST), which has some of the longest distances between gates of any airport in the world. PKX will become a major hub for the SkyTeam alliance, as it'll be home to SkyTeam members such as Air France, KLM and Delta plus local giant China Eastern. China Southern, which will leave the SkyTeam alliance at the end of this year, is expected to eventually move all operations from PEK to PKX.

Remaining at PEK Airport will be local Star Alliance member Air China, though it has been given some slots at PKX as well.