The nation's largest domestic air carrier says it is removing the grounded Boeing MAX 737 planes from its schedule through April 13.
The previous date for its return to Southwest was March 7, but that date has been moved since it appears that it will take longer than previously expected for the troubled planes to get back in the air.
This is the second U.S. airline in less than a week to extend the time frame for the MAX return.
Last week, American Airlines took the plane out of its schedule until April 7.
Both airlines are taking the step so they don't have to cancel flights at the last minute if the FAA further delays the MAX's return. United is likely to follow suit.
Southwest said it will proactively cut 300 daily flights, out of a total of more than 4,000.