Chinese military and civil air traffic control authorities worked to ease the concerns of thousands of passengers after days of flight delays and cancellations that have seen many travelers choose alternative means of transportation, including high-speed trains.

The authorities said they have optimized plans for airspace controls to boost the capacity of East China's airports during military drills, according to an announcement posted on the official website of the Civil Aviation Administration of China.

A red alert for air traffic delays was issued on Monday, advising that eight airports in East China would not be able to receive arriving flights between 2 pm and 6 pm, and that the two major airports in Shanghai - Hongqiao and Pudong - would see handling capability cut by 75 percent.

The duration of the impact was shorter than the previously forecast four hours to only one hour from 2 to 3 pm. It had been estimated that only 25 percent of flights in East China would operate normally during those four hours, but actually more than 60 percent were operating as scheduled from 2 to 3 pm and more than 70 percent after 3 pm.

Some flights were canceled because of rainstorms.

Extreme weather is the most frequent reason for flight delays in July and August. The impact of military drills on civil flights was minimal, the People's Liberation Army Daily reported.

The CAAC reduced Tuesday afternoon's flight delays from its highest to the second-highest alert, and then lifted the lower alert at 3:30 pm as widespread delays in East China ended and traffic started flowing normally again.

"Air traffic at Shanghai airports and other airports in the East China region went back to normal on Tuesday afternoon as joint efforts were made by military and civil affairs authorities to minimize the impact," the CAAC said on its website.

Travelers said the authorities' advance announcements, along with easy access to flight data, helped them get through the flight delays and cancellations more easily.

Some travelers used smartphone applications and Web connections to keep themselves updated with the latest information.

Liu Wenhao, a 46-year-old accounting specialist in Shanghai, said his flight from Shanghai to Dalian was delayed for about an hour, but the flight information applications provided notification of new schedules.

Passenger flow in two airports in Shanghai remained stable and normal, according to Shanghai airport authorities.

Wang Ying in Shanghai contributed to this story.

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