By David Kerley and Jeffrey Cook Apr 3, 2019 5:04 PM
The Ethiopian Airlines Boeing 737 MAX,
which crashed in March and killed 157 people, suffered a damaged angle-of-attack sensor upon takeoff from a bird or foreign object, triggering erroneous data and the
activation an anti-stall system -- called MCAS -- sending the pitch of the plane downward and ultimately crashing into the ground, two aviation sources familiar with the investigation told ABC News.
As the
jet was nose diving, the Boeing 737 MAX pilots did not try to electronically pull the nose of the plane up before following Boeing's emergency procedures of disengaging power to the horizontal stabilizer on the rear of the aircraft, according to the sources.
One source told ABC News that they manually attempted to bring the nose of the plane back up by using the trim wheel. Soon after, the pilots restored power to the horizontal stabilizer.
With power restored, the MCAS was re-engaged, the sources said, and the pilots were unable to regain control and the plane crashed.
The
preliminary findings in the crash investigation are
expected to be released by
transportation officials in Ethiopia on Thursday morning.