BEIJING — China's airlines and airports continue to have the worst flight delays in the world, according to a travel industry monitor.

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 just 18.3 percent, FlightStat Inc. reported on its website.

Shanghai was slightly better at 28.72 percent, but still 10 percentage points below the next-worst performer, Istanbul.

Among airlines, mainland Chinese carriers made up eight of the 10 worst performing airlines. Flag carrier Air China came in sixth from the bottom, with just 54.58 percent of its flights arriving on time.

No reasons were given for the poor performance, although industry analysts frequently 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. Alongside that growth, routine delays, shoddy service and ill-mannered passengers have fueled an epidemic of air rage incidents, video footage of which is often shown on television.