Investigators looking into the fatal Ethiopian Airlines crash involving a Boeing 737 Max plane are said to have reached a preliminary conclusion that an anti-stall system on board misfired, the Wall Street Journal reported Friday.
Based on data retrieved from the flight's black boxes, the stall prevention system — known as the MCAS, or Maneuvering Characteristics Augmentation System — activated automatically before the plane nose-dived into the ground, the Journal said, citing people briefed on the matter.
Those sources told the WSJ the preliminary finding is subject to revisions and one of the people said the U.S. government air-safety experts have been analyzing details gathered from the Ethiopian investigators.
Boeing did not immediately respond to a request for comments sent outside office hours.
Earlier this month, the Ethiopian Airlines Flight 302 bound for Nairobi crashed shortly after take-off, killing all passengers and crew members on board.
It was the second fatal incident involving a Boeing 737 Max — the plane manufacturer's new, top-selling jet — since October when a Lion Air flight, which took off from the Indonesian capital, Jakarta, crashed into the sea.
Many believe that in both instances, the MCAS constantly pushed the nose of the plane down despite the pilots' repeated attempts to correct the move. It is suspected to have had a role in causing the crashes on both the Ethiopian Airlines and Lion Air flights.
The 737 Max jets have been grounded since mid-March.
On Wednesday, Boeing outlined fixes to the MCAS by updating the plane's software, cockpit alerts and pilot training. Those plans are set to be sent to the Federal Aviation Administration for certification and approval after which, Boeing will send the software updates to customers.
But regulators around the world would have to sign off on the safety of the 737 Max before it is allowed to carry passengers again. That could take weeks to happen.
— CNBC's Phil LeBeau contributed to this report.