The pilots of the doomed Lion Air flight that crashed into the Java Sea October 2018 frantically searched the aircraft's manual to try to find a way to keep the plane under control before the crash, cockpit voice recordings show.
The first officer reported a "flight control problem" two minutes into the flight, and the captain then asked him to check a handbook that contained procedures for abnormal events, the recordings showed, according to a report from Reuters.
The Boeing 737 Max 8 plane then spent nine minutes pushing its nose down, with the first officer unable to control the plane, as the captain desperately searched the handbook for a solution.
The plane then crashed into the sea, killing all 189 people on board.
Three sources discussed the contents of the plane's cockpit voice recorder with Reuters, in the first time that such information, which is part of an ongoing investigation into the crash, has been made public.
The investigation has taken on new significance after an Ethiopian Airlines Boeing 737 Max 8 crashed on March 10, 2019, killing all 157 people on board.
The French air-accident investigation agency BEA said the two crashes showed "clear similarities," and Boeing is introducing a software upgrade to its new anti-stall system that has come under scrutiny after the two crashes.
The preliminary report into the Lion Air crash mentioned the Boeing system as well as other factors, including the airline's maintenance.
A source told Reuters that someone mentioned the plane's airspeed on the cockpit voice recording, and a second source said one of the plane's indicators showed a problem on the captain's display but not the first officer's.
The preliminary report showed that the plane's computer kept pushing the nose of the plane down using the trim system, which is a system that usually adjusts the aircraft to keep it on course.
A source told Reuters that the trim system was not mentioned in the recording, just the airspeed and altitude of the plane. "They didn't seem to know the trim was moving down," the source said.
A crew that flew the same plane the evening before had the same problem with the plane's nose but ran through three checklists to solve the problem, the preliminary report showed.
The plane was treated on the ground, and the report says the previous crew believed the issue was resolved.
Bloomberg reported on March 19, 2019, that an off-duty pilot riding in the cockpit of that flight fixed a malfunction that allowed the plane to land safely.
Following the Ethiopian Airlines crash, many countries have grounded the 737 Max, including China, which has a higher number of the aircraft than any other nation. The US was the most recent country to ground the plane.
Boeing declined to comment to Reuters because of the ongoing investigation.
This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.
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