A Boeing 737 jetliner carrying 153 passengers and nine crew members and landed safely in Dalian after it suddenly dropped to more than 6,500 meters all of a sudden in mid-flight, the country's civil aviation regulator said Thursday.
The Air China flight from Hong Kong to Dalian is said to have lost its altitude rapidly and oxygen masks dropped in the cabin. The flight took place on Tuesday, July 10, 2018.
However, after the horrific event, the plane then returned to cruising altitude and continued as scheduled.
On the other hand, speculations coming from the local media stated that "the crew had been smoking in the cockpit" which caused for the sudden mishandling of the ventilation system.
Meanwhile, the Chinese aviation authorities are examining both the flight data recorder and the cockpit voice recorder to determine what caused the incident.
Several passengers on board the Tuesday flight have posted pictures of the dropped oxygen masks on social media.
Passengers were told to fasten their seat belts and told that the plane had to descend based on the posts on social media.
If a plane loses cabin pressure, the pilot has to bring the aircraft to a lower altitude to keep crew and passengers safe.
"These planes fly at an altitude that, at Mount Everest is called the death zone, because of a lack of oxygen," aviation expert Greg Waldron of Flight Global told news sources.
"So the pilot absolutely has to bring the plane lower. Otherwise, crew and passengers would become unconscious."
Upon discovering their error, the crew turned the switches back on. The plane climbed to around 7,500 meters (24,600 ft) and flew to its destination with a less-than-adequate oxygen level in the cabin, according to state media.
Air China said on Wednesday, July 11, 2018 that the crew is being investigated by the Civil Aviation Administration of China (CAAC).
"If the investigation discovers crew behaviors that have violated rules and regulations, we will adopt a zero-tolerance attitude and seriously punish those found responsible," the airline said in a statement.
