After the captain heard a deafening sound, he looked over and noticed the right windshield was missing.
"There was no warning sign".
"The windshield cracked suddenly and gave a huge bang".
Pictures shared online show the co-pilot's side of the windshield gone and it emerged that he was nearly sucked out of the window by the sudden loss of pressure.
Everything in the cockpit was floating in the air. Many devices were malfunctioned and the plane was jolting strongly. "The plane was shaking so hard I could not read the gauges", the pilot said, adding that the cockpit's temperature dropped to minus 40 degrees Celsius.
Calls to Liu's cellphone by China Daily went unanswered on Monday evening.
Sichuan Airlines said on its official Weibo account that the flight had experienced a "mechanical failure" without providing further details.
Sichuan Airlines 3U8633 was en route from Chongqing in south-west China to Lhasa in Tibet when the incident happened.
A common cause of windshields shattering is severe hailstorms. It lasted for about five, six seconds.
Passengers were being served their breakfast when the plane plunged suddenly to 24,000ft.
Later, the captain spoke to the Chengdu Economic Daily about the ordeal. "People were shocked", the agency quoted an unnamed passenger as saying.
Mobile phone footage emerged online showing flight attendants asking passengers to wear oxygen masks and put on safety belts. "When we finally landed, some of the women were in tears", he said.
A Sichuan Airlines co-pilot was sucked halfway out of an aircraft's cockpit when its windshield shattered during a flight, Chinese state media has reported. Chinese social media users praised the pilots for landing the flight safely without incurring any passenger injuries.
"The pilot stayed calm, responded quickly and correctly to drop the aircraft to an altitude where emergency oxygen is not needed and handled the situation with strong skills".
Liu later said the accident reminded him of a similar incident with British Airways in 1990, when a windshield separated from its frame, and the captain was sucked out of the plane.
Despite these difficulties and the intense cold, the pilot managed to slow the aircraft from its original speed of about 800-900 kph and land in about 20 minutes.
In a statement, the Civil Aviation Administration of China said that part of the cockpit window broke as the plane was flying over Chengdu and the cause of the incident was under investigation.