Pilots on board Ethiopian Airlines flight 302 battled the plane's automated trim system for nearly the entire duration of the 6-minute flight, according to a preliminary report obtained by CNN Thursday.
The pilots, unable to stabilize the 737 Max 8 plane even after following the emergency procedures recommended by Boeing, tried together to pull the airplane's nose up repeatedly during the last moments of the flight, the preliminary report revealed. But the downward force of the aircraft was too great for the flight crew to overcome.
The pilot called out "pull up" three times to tell the second-in-command to raise the nose, and both pilots tried to pull the nose up together to keep the plane flying, but they were unable to regain control.
The problems on board the Ethiopian Airlines flight mirror those encountered on the doomed Lion Air flight 610 -- which operated the same 737 Max 8 model and crashed in November -- in what could be a major blow to Boeing as it struggles to get the aircraft back in service.
Timeline of the flight, detailed in the preliminary report, reveals that the pilots' struggle to control the plane began moments after it left the ground.
Seventy seconds after takeoff from Addis Ababa's Bole International Airport on March 10, one of the angle of attack sensors on board the aircraft began providing faulty information to the aircraft's systems, indicating an imminent stall to the flight crew.
The stick shaker on the pilot's yoke -- another system intended to warn a pilot of an imminent stall -- began shaking the yoke. Incorrectly sensing a stall, the aircraft's system tried to force the nose down four separate times during the flight, in the end overpowering the flight crew's ability to keep the airplane climbing.
Recognizing a problem with the automatic trim, the pilots followed emergency procedures and turned off the system. Instead, the pilots tried to use the backup manual trim wheel to adjust the trim, but the airplane was traveling too fast and the manual trim wheel would have been physically impossible to operate.
Less than two minutes later, Ethiopian Airlines flight 302 crashed, killing 157 passengers and flight crews.