Boeing tested software changes to the 737 max planes over the weekend.
A person briefed on the tests said pilots from the three U.S. carriers that fly the planes tested software changes to a key stabilization system on Saturday.
The changes are meant to decrease the chances of triggering the maneuvering characteristics augmentation system.
It’s believed the system played a role in the lion air crash in Indonesia in October.
Multiple airline sources said pilots and training officials from the three airlines met with Boeing officials Saturday in Seattle.
They did simulated flights using the current and updated software.
A person briefed on the tests said each pilot using the flight simulator landed the plane safely.