On March 31, 18 flights returned to their departure points in southwestern Yunnan province, affecting more than 1,000 passengers. Media reports said that the pilots, who work for China Eastern Airlines' Yunnan branch, were protesting over their pay and working conditions. In the past years, more and more pilots put forward resignation. What lies behind it is a pilot shortage and the out-of-date pilot management system in China. China has 12,000 civil pilots. But official figures predict that the total number of flights would increase 80 percent by 2010 and 6,500 more pilots would be required.