The pilots of the doomed Boeing 737 MAX that crashed in Ethiopia last month followed the plane maker’s emergency procedures but still failed to recover control of the jet, The Wall Street Journal reports. Citing people familiar with the investigation into the accident, which killed all 157 people on board, it’s reported that the pilots turned off a flight-control system that was automatically pushing down the plane’s nose shortly after takeoff. However, the crew couldn’t get the aircraft to climb and turned the system back on before the final plunge. The version of events has yet to be officially confirmed, but it throws into doubt assertions by Boeing and the U.S. Federal Aviation Administration that following established procedures could prevent crashes in similar incidents. It’s not clear why the pilots turned the system back on—but officials suggested it was because manual controls to raise the nose didn’t work.