The airline had previously planned to reintroduce its MAXes into service on Sept. 2. In a statement, Southwest said it "continues to await guidance from Boeing and the Federal Aviation Administration (FAA) on the impending 737 MAX software enhancements and training requirements."
On Wednesday, the FAA acknowledged that simulator testing of the MAX had revealed a new issue that had to be resolved before flight testing, and eventually recertification, could occur.
Southwest's statement added that the airline remains "confident that, once certified by the FAA, the enhancements will support the safe operation of the MAX."
American and United Airlines both previously announced that they would return their MAXes to service in September, but American's CEO signaled that he was prepared to further delay the aircraft's return to service in the coming weeks.
