The US Federal Aviation Administration (FAA) has approved major software fixes and changes to pilot training for Boeing’s 737 MAX airliners that were grounded after two fatal crashes, local media said.

The changes are aimed at fixing problems with a flight-control system, according to The Wall Street Journal, which cited internal government documents and people familiar with the details.

The jet’s automated stall-prevention system, believed to have caused an Indonesian plane to crash last October, will be revised to make it less aggressive and more controllable by pilots, who will receive enhanced training. 

The planes were grounded after an Ethiopian Airlines plane crashed less than five months after the Indonesian one, killing 157 people on board. Around 20 countries shut their airspace to all Boeing 737 Max 8 jets following the air disaster.