People stand near debris at the crash site of the Ethiopia Airlines flight in Ethiopia, on March 11, 2019.

  • Investigators have reached the preliminary conclusion that an automated anti-stall system played a part in the fatal crash of a Boeing 737 Max operated by Ethiopian Airlines, The Wall Street Journal reported.
  • A flaw in the plane's software system has been the main theory behind the crash, which killed 189 people in March.
  • Reports on an earlier 737 Max crash, a flight run by Lion Air in October, have pointed towards the same anti-stall system.
  • Boeing has developed software updates and pilot training around the system, but it has yet to be implemented. In the meantime the 737 Max is grounded.

Officials investigating the Ethiopian Airlines Boeing 737 Max crash have reportedly reached a preliminary conclusion that the plane's automated anti-stall system activated during the disaster.

A fault in the plane's software has been the most widely-discussed theory for the Ethiopian Airlines crash that killed 189 people in March, and also the Lion Air 737 Max crash that killed 157 people in October 2018.

People briefed on the preliminary conclusions told The Wall Street Journal that the plane's Maneuvering Characteristics Augmentation System (MCAS), which is designed to automatically stop the plane from stalling by pointing the nose of the plane downward, automatically activated during the fatal flight.

Read more: Boeing just unveiled how it's going to fix the 737 Max that was grounded after 2 fatal crashes in recent months

The preliminary findings, reached through an analysis of the plane's black box, is subject to change, people briefed on the matter told the Journal. They were shared at a high-level briefing at the Federal Aviation Administration on Thursday.

The preliminary report for the Lion Air crash also found that the MCAS system repeatedly pushed the nose of the plane down, leaving the pilot wrestling with the controls as it crashed into the sea.

Ethiopia's Transport Minister said earlier this month that data from the black boxes of both planes show "clear similarities."

Read more: A cockpit voice recording from doomed Lion Air 737 Max shows pilots scoured the plane's manual to fix its fatal dive but couldn't find the right procedure in time

Boeing unveiled a software fix and new training procedures for the 737 Max on Wednesday in a bid to fix the planes, which have been grounded around the world after the two deadly crashes.

Most of the updates are to the MCAS system, which is triggered by the plane's angle-of-attack (AOA) sensor, which measures the plane's orientation in the air.

The updated software will "provide additional layers of protection if the AOA sensors provide erroneous data."

Boeing said that the software updates have been put through hundreds of hours of analysis, laboratory tests, and simulator trials, as well as two test flights.

Boeing is still working with the FAA to get the software and training updates certified, and the EU and Canada are also conducting their own reviews to the upgrades. The planes will remain grounded until this certification takes place and pilot training is complete.

The acting head of the FAA told Congress on Wednesday that Boeing was allowed to oversee much of the certification of its software itself, as part of a longstanding policy mandated by Congress that is now under increased scrutiny.

Read more: FAA boss admits letting Boeing partly self-regulate the software thought to be behind both fatal 737 Max crashes

Daniel Elwell defended the process, and said that FAA had initially overseen the software's certification before backing off. He said more authority was given to Boeing when it had "the comfort level" that the manufacturer could oversee the system.

But one lawmaker accused the FAA of doing "safety on the cheap" and an internal watchdog said the current system will change and said the FAA's certification of the 737 Max will be investigated.

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