On May 14, China's aviation authorities promised to make greater efforts during this summer's thunderstorm season to ease air travel delays -- which have in the past led to violent confrontation at airports.

China's main air traffic control centre has installed new equipment that will be able to alert the main airports in Beijing, Shanghai and Guangzhou up to 48 hours in advance of storms, to help airlines better prepare, the Civil Aviation Administration of China said on its Web site.

The authorities also said they would improve coordination with the military, which controls almost all of China's airspace, to open temporary routes around storms and "reduce the effect on regular flight operations".

Chinese airports regularly shut down during rain storms, delaying flights for hours and stranding thousands of passengers.

Airports have now taken to putting up posters and showing short movies explaining why weather can delay flights and asking that people not attack ground staff or try to storm grounded aircraft, as has happened in the past.

But passengers say Chinese airlines and airports only add to the confusion by keeping them in the dark about delays and refusing to provide information about rescheduled flights.

Air travel has boomed along with the economy, but service standards and infrastructure have struggled to keep up.