WASHINGTON, April 11 (Reuters) - The Federal Aviation Administration will hold a meeting Friday with major U.S. airlines that fly now grounded Boeing 737 MAX airplanes and three major pilots’ unions, the agency confirmed.

The meeting with safety representatives from the airlines and unions is set for three hours at FAA headquarters in Washington and will include American Airlines, United Airlines and Southwest Airlines Co and officials from the three unions.

More than 300 Boeing 737 MAX jets have been grounded worldwide after nearly 350 people died in two crashes, one in Indonesia in October and one in Ethiopia last month. The FAA is also convening a joint review with aviation regulators from China, Europe, Canada, Brazil, Indonesia, Ethiopia and other countries.

American and United have canceled flights through early June, while Southwest has canceled flights until the end of May because of the 737 MAX grounding.

Boeing said it has reprogrammed software on its 737 MAX passenger jet to prevent erroneous data from triggering an anti-stall system that is under mounting scrutiny following the two deadly nose-down crashes and revised pilot training. On April 1, Boeing said it delayed submitting the proposed revisions to the FAA for approval.

The FAA said the meeting is to help “the FAA to gather facts, information, and individual views to further understand their views as FAA decides what needs to be done before returning the aircraft to service.” The FAA added it “continues to gather all available information and data in considering the return of the 737 MAX to service.”

Dennis Tajer, spokesman for the Allied Pilots Association that represents pilots at American Airlines, said he expected the union would be able to “provide feedback and input regarding pilot training related to the 737 MAX.” The airlines did not immediately comment.

Federal prosecutors aided by the FBI, the Transportation Department inspector general’s office and a blue-ribbon panel are also reviewing the plane’s certification and other issues surrounding the 737 MAX.

Lawmakers and the National Transportation Safety Board are also reviewing the FAA’s certification process that delegates some tasks to the airplane manufacturers. (Reporting by David Shepardson in Washington Editing by James Dalgleish)