US aviation regulators announced two new steps to tighten the process of approving airliner designs, actions required by Congress after crashes on Boeing Co. 737 Max aircraft killed 346 in 2018 and 2019.

The Federal Aviation Administration’s policy changes will take effect in 30 days after the public and industry have a chance to comment on them, the agency said in a press release on Wednesday.

The FAA will establish stricter requirements for planemakers to inform the agency of unusual designs that require extra scrutiny during its process of evaluating aircraft designs, it said.

The actions are among multiple moves ordered by lawmakers to address concerns raised in investigations of the crashes, which occurred off the coast of Indonesia and in Ethiopia. As the updated 737 Max family was being designed, Boeing officials altered a safety system that could push down the plane’s nose, but didn’t explain it to FAA engineers.