The captain and the first officer struggled as the 737 Max 8's systems, designed to prevent the plane stalling, repeatedly forced the nose of the plane down. For nearly six minutes, the report shows, the pilots worked through a series of procedures to try and regain control of the plane.
In the end, after the pilots had turned back, the automated system pitched the plane into a steep dive from which it was impossible to recover, and it crashed into the ground.
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 October -- in what could be a significant blow to Boeing as it struggles to get the aircraft back in service.
Unable to stabilize the 737 Max 8 plane even after following the emergency procedures recommended by Boeing, the pilots tried together to pull the jet'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 to overcome.
The captain called out "pull up" three times to tell the first officer to raise the nose. Both pilots tried to pull the nose up together to keep the plane flying, but they were unable to regain control. The aircraft's automated systems lowered the nose four times during the flight.
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 October -- in what could be a major blow to Boeing as it struggles to get the aircraft back in service.
The report on the Ethiopian Airlines crash does not specifically name the Max 8's plane's anti-stall system -- called the Maneuvering Characteristics Augmentation System (MCAS) -- which is suspected to have contributed to the Lion Air disaster. But its findings make it likely that the MCAS system pushed the plane into a dive fueled by erroneous angle of attack sensor readings.
Boeing is currently working on a change to the system's software. The company acknowledged the similarities between the two crashes in a statement Thursday. "The preliminary report contains flight data recorder information indicating the airplane had an erroneous angle of attack sensor input that activated the MCAS function during the flight, as it had during the Lion Air 610 flight," the statement said.
"To ensure unintended MCAS activation will not occur again, Boeing has developed and is planning to release a software update to MCAS and an associated comprehensive pilot training and supplementary education program for the 737 MAX."
Speaking before the release of the report, Ethiopian Minister of Transport Dagmawit Moges suggested that Boeing review "the aircraft flight control system related to the flight controllability."
She told reporters in Addis Ababa that said her agency would recommend that aviation authorities verify that Boeing has "adequately addressed" flight control issues "before release of the aircraft to operations."
The preliminary report, which has not yet been publicly released, does not come to a finding of probable cause. A final report could take as long as a year to produce.
The 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.
https://www.cnn.com/2019/04/04/world/ethiopian-airlines-crash-preliminary-report-intl/index.html
2019-04-04 18:06:00Z
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