DALLAS, Texas (CBSDFW.COM/AP) — It looks like the three big U.S. airlines that own Boeing 737 Max jets will have to go through another summer without the planes.

That means Southwest, American and United will likely cancel thousands more flights during their busiest time of year. Still, the airlines are remaining very profitable thanks to strong demand for travel, which is pushing up average prices and leaving fewer empty seats on planes.

The grounding came amid an on-going uncertainty about the plane’s return to service after two deadly crashes killed hundreds of travelers last year.

American Airlines earned $414 million in the fourth quarter, and Southwest earned $514 million.

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)