Southwest has extended the cancellation of its Boeing 737 Max planes to early June, joining the two other U.S. carriers with the beleaguered planes in their fleets — American and United — each of which have done the same.

The planes have been grounded around the world since March 2019 following two fatal crashes in Indonesia and Ethiopia that killed a total of 346 people.

On Thursday, Southwest said in a statement it would remove the Boeing planes from its flight schedule through June 6. It said this was “based on continued uncertainty around the timing of MAX return to service, as well as Boeing's recommendation for Pilot simulator training.”

The airline added: “We remain confident that, once certified by the FAA, the enhancements will support the safe operation of the MAX.”

This move will result in about 330 weekday flights removed from the carrier’s schedule of more than 4,000 daily flights, according to Southwest.

Southwest had 34 of the 737 Max planes in its fleet, according to USA Today, and was expected to add another 41 by the end of last year. And it’s possible that the plane’s return to service may be prolonged even further because Boeing has recommended that pilots complete more rigorous pilot simulator training, the paper noted.

Southwest plane
Credit: Getty Images

Earlier this week, American Airlines said it was pushing the 737 Max from its schedule until June 4. And last month, USA Today also reported United Airlines removed the planes through June 4 as well.

Several airline executives have previously said they will conduct their own tests once the planes are certified as safe to fly before commercial passengers are asked to board.

“Once the aircraft is certified, American will run flights for American team members and invited guests,” American Airlines said in its statement this week.

In December, Boeing fired its CEO as the crisis surrounding the grounding of what was once the manufacturer’s best-selling plane continued. A week before his firing, the company decided to temporarily halt production of newer 737 MAX planes.