---- Ein Flugzeug von China Southern Airlines ist am Internationalen Flughafen Shanghai Hongqiao in Shanghai, China, 7. Juli 2012 gesehen. Bereits Asias bi
--FILE--A plane of China Southern Airlines is seen at the Shanghai Hongqiao International Airport in Shanghai, China, 7 July 2012. Already Asias biggest aircraft buyer, China is developing its own passenger planes and building scores of airports but its aviation expansion faces turbulence from slowing growth and inadequate infrastructure. As the countrys carriers spend billions on jets to serve a growing middle class taking to the skies in ever-increasing numbers, passengers face constant delays and longer flight times owing to military limits on airspace and poor management. Three of the mainlands airports are among the worlds 20 busiest, with Beijing in global second place on 78 million passengers a year, behind only Atlanta in the United States. At the same time, Beijing was worst in the world for delays last year with only 18 percent of flights on time, followed immediately by Shanghai, according to the website www.flightstats.com. The countrys airlines carried 350 million passengers last year, up nearly 11 percent from 2012, official figures show, and the countrys civil aviation authority said it will have more than 230 airports by 2015, up from 193 last year.