A flight from Zhoushan in East China's Zhejiang province to Chengdu in Southwest China's Sichuan province was diverted to Ningbo in Zhejiang just after takeoff due to a mechanical failure, according to online posts.

Flight 3U6960 of Sichuan Airlines took off from Zhoushan airport at around 18:58 and was expected to arrive at Chengdu Tianfu International Airport at 23:20 on Sunday, according to the one-stop self-service flight app Umetrip.

However, the plane had to land in Ningbo after enacting emergency code 7700 soon after the takeoff, according to Umetrip.

A customer service personnel from Ningbo Lishe International Airport told Shangyou News, a news outlet headquartered in Chongqing, which the plane made a diversion in Ningbo due to a "reason of the airlines," and another plane replaced the former one for the flight and took off from Ningbo at 00:39 on Monday.

The flight finally arrived at Chengdu Tianfu International Airport at 4:22 am, some 5 hours late, according to Umetrip.

A customer service personnel from Sichuan Airlines said that the flight has landed safely, and during the journey, the plane landed in Ningbo in diversion, but the person knew little of the reason.

A passenger said that noises arose on the plane 10 minutes after the takeoff and there were no other abnormalities, and the crew later informed them for the diversion in Ningbo. After landing in Ningbo, it is said that there may be an engine malfunction.

7700 code is an emergency code used in airlines, indicating an emergency situation, such as mechanical failure, medical emergency on board, etc. This code is to get the airway priority from ATC (Air Traffic Control) for relevant support.