Pilots on the Ethiopian Airlines flight that crashed last month followed protocol set by plane maker Boeing to manually disable an automated anti-stall system as they tried to save the Boeing 737 Max jet, a person familiar with the situation said.
The Manuevering Characteristics Augmentation System (MCAS) turned itself on numerous times during the short flight, the person said. MCAS, which is programmed to push down a plane's nose to help prevent aerodynamic stalls in some situations, is a focus of concern by regulators and lawmakers after 346 people died in crashes of Boeing's newest version of the 737 flown by Ethiopian and Lion Air less than five months apart.
The Wall Street Journal reported earlier that the pilots on the deadly flight initially followed the emergency procedures laid out by Boeing, cutting power to electric motors driven by the automated system.
The newspaper said pilots turned electric power back on after cranking a manual wheel that turned the same movable surfaces on the plane's tail that MCAs had affected.
A Boeing representative in Singapore said she wasn't able to comment, adding that the accident is under investigation and questions should be directed to the investigators in charge. An Ethiopian transport ministry spokesperson didn't respond to requests for comment.
A preliminary report into the Ethiopian Airlines crash is nearing release but the exact timing is uncertain. The two disasters have rocked the credibility of Boeing as well as US regulators who approved the new plane.
Regulators around the world grounded the 737 Max, Boeing's fastest-selling plane ever, before the US Federal Aviation Authority followed suit.