Air China flight attendants have been accused of being ‘sloppy and careless’ after a plane was photographed in flight with its door not properly locked. The photo of the Boeing 737-800 was snapped this month at Beijing Capital International Airport and went viral after it was uploaded onto Chinese social media networks. It showed the door’s lock out of position while the plane was in the air at China’s busiest airport, drawing criticism from air safety experts. This photo showing a plane door's lock out of position went viral on Chinese social media networks . Air safety expert Guang Yu told local media: ‘It is probably not dangerous because there are various safety measures in place but it shows an extremely sloppy and careless attitude on behalf of the cabin crew.’ Chinese state media agency Xinhua quoted an Air China spokesman as saying that the airline conducted a thorough investigation, including interviews with the plane’s crew and other staff, after the photo surfaced online. It said the investigation found that the lock was in the ‘normal’ position when the flight took off. A Boeing specialist quoted by Chinese state media said that human error or a mechanical problem with the lock could result in an external lock being out of position. Air China said an investigation found that the lock was in the proper position when the flight departed . The expert added that a mechanical problem would not affect flight safety because of another locking system operated from within the cabin. The report also said that it appeared to be a case of mechanical failure. The photo sparked debate on Chinese social media website Weibo, and was shared after several incidents involving Chinese passengers opening plane doors before take-off or after landing. Last week a 42-year-old Chinese man was detained for 10 days after he opened an emergency exit shortly before a Urumqi Airlines plane was due to take off. The man told authorities that he thought the door handle was a handrail that he could grab onto for support, ‘like the handrail on a bus’. A Urumqi Airlines flight was delayed last week after a passenger opened the emergency exit . He was removed by police and detained for causing a disruption for others on board the plane, which was travelling from Urumqi to Zhengzhou. That incident was at least the fifth time since December a passenger has opened an emergency exit on a plane in China. Last month, an unidentified man was detained for 10 days after opening a plane emergency exit as passengers were boarding at Nanjing airport, the South China Morning Post reported. He told airline staff ‘The door is not important’ when they asked him why he opened the door, the newspaper reported. In January, angry passengers opened emergency exit doors on a China Eastern flight in Chengdu . In January, angry passengers opened emergency exit doors in protest of a weather-related delay as their China Eastern flight taxied to a runway in Chengdu. It led to a longer delay for everyone on board. A month earlier, a man was arrested after he opened the emergency exit ‘to get off quicker’ after a China Eastern flight landed in Hainan. By unlocking an opening the emergency exit, he deployed the emergency slide. Also in December, a rookie traveller yanked open a door on a Xiamen Air flight from Hangzhou to Chengdu to ‘get some fresh air’ shortly before it was supposed to take-off.
Air China said it conducted an investigation after the photo surfaced . It said that the lock was in the 'normal' position during take-off . Photo sparked debate on Chinese social media after recent incidents . Passengers have opened emergency exits on at least five occasions .