(CNN) – Boeing has been under fire following two fatal crashes within five months involving the 737 Max plane, including the March 10 Ethiopian Airlines crash that killed all 157 people on board.
Now the aircraft manufacturer is testing new software patches to prevent future crashes. Meanwhile, some American carriers are warning that flights will continue to be canceled as the new software is tested.
More than 370 planes remain grounded worldwide as Boeing tests the software changes for their 737 Max planes.
The Federal Aviation Administration grounded them indefinitely after two of the planes crashed, killing more than 300 people.
Ethiopian Airlines is among the many anxious for answers.
The causes of both crashes haven’t been officially determined, but the focus has been on an automatic safety feature that may have incorrectly forced the nose of each plane to dip.
Over the weekend, pilots and training officials from multiple airlines met with Boeing officials in Seattle to test the changes, according to a person briefed on the tests.
As of Monday, Southwest Airlines is canceling flights five days out as a result of the groundings, while American Airlines is canceling about 90 flights a day through April 24.