Two workers walk under the wing of a 737 Max aircraft at the Boeing factory in Renton, Washington, March 27, 2019.

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.