A travel industry monitor says China's airlines and airports lead the world in flight delays.

FlightStat Inc. reported on its website that a survey of flight times last month showed that Beijing's airport had the lowest proportion of flights leaving on-time among 35 leading airports at 18.3 percent. Shanghai was second worst at 28.72 percent. Mainland Chinese carriers made up eight of the 10 worst performing airlines, including among them flag carrier Air China.

No reasons were given for the poor performance, although industry analysts largely blame the air force's tight restrictions on airspace for heavy congestion along available corridors.

Air travel has more than quadrupled in China along with rising incomes and cheaper tickets. Frequent delays, shoddy service and ill-mannered passengers have fueled an epidemic of air rage incidents.