Despite the improvement, however, passengers said that they have not noted any changes for the better.

Still, civil aviation officials, experts and airlines argued that the improvement was hard-earned, given increasingly busy air traffic.

The country's air transport fleet increased by 150 planes last year. The Air Traffic Management Bureau recorded a growth of 7.6 percent in the number of flights it handled, which reached 6.07 million last year.

"Just like on the highway, more cars will cause traffic jams. More planes flying in the sky will also produce congestion and delays," said Li Xiaojin, professor at Civil Aviation University of China.

The authority needs to control the purchase of planes and refine air traffic management to allow more planes to pass through quickly, he added.

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