“The plane did what it was told to do by someone in the cockpit,” an unidentified person who is familiar with the preliminary assessment told the newspaper.

Officials are now investigating the cockpit crew, as well as the possibility of someone breaching the cockpit. China Eastern told the WSJ that there is no evidence of problems with the health, financial status or family of the pilots aboard.

>> Photos: China Eastern flight carrying 132 people crashes in Guangxi

China Eastern said that a possible cockpit intrusion “wasn’t plausible” when asked. In most emergencies, pilots will enter a code into the aircraft’s transponder, usually “7700,” to notify air traffic control and other aircraft of an emergency. Chinese authorities said no emergency code was sent from the plane.

The airline also told the newspaper that there was no evidence of problems with the aircraft. Boeing also has not issued any safety directives as a result of the crash, according to the Wall Street Journal.

The crash

The China Eastern Boeing 737-800 was carrying more than 132 people when it crashed in Guangxi province, causing a fire on a mountainside on March 21. No survivors were found among the wreckage.

Prior to the crash, Flight 5735 was en route from Kunming to Guangzhou around 2:30 p.m. local time, cruising at just over 29,000 feet, when the aircraft suddenly pitched down dramatically.

For almost two minutes, the aircraft accelerated toward the ground, reaching speeds of over 600 mph with a vertical descent rate up to 30,000 feet per minute. The aircraft recovered briefly at one point, but then resumed its dive.

The crash left a 65-foot-deep crater in a mountainside and set off a forest fire. More than 49,000 pieces of plane debris were found, according to The Associated Press. It took two days to find the cockpit voice recorder and six days for the flight data recorder, which was buried more than five feet underground.

The incident happened during the cruise portion of the flight, which according to Reuters is rare. Boeing said that only 13% of deadly commercial accidents globally from 2011 to 2020 happened during the cruising portion of flights. In comparison, 28% of deadly incidents happened on final approach and 26% on landing.

Typically, the aircraft is flying on autopilot during this portion of the flight.

Chinese aviation expert Li Xiaojin told Reuters that “usually the plane is on autopilot during cruise stage. So it is very hard to fathom what happened.”

An initial report issued in April by the Civil Aviation Administration of China said no abnormalities had been found in the plane or its crew, or external elements such as bad weather.

China Eastern, one of four major Chinese airlines, and its subsidiaries grounded all their Boeing 737-800s — more than 200 planes — following the crash but have since returned them to service.

The crash was one of China’s worst air disasters in a decade.