Southwest Airlines on Friday again pushed back its timeframe for resuming flights on the Boeing 737 MAX, this time through March 6, 2020.
The domestic-focused US carrier, which had previously set February 8 as a return date for the MAX, said "proactively" removing the aircraft from service reduced the likelihood of last-minute cancellations and disruption.
The planes have been grounded globally since mid-March following two crashes that killed 346 people. Boeing has said it expects to receive regulatory approval to resume flights in the fourth quarter of 2019.
"Southwest Airlines continues to monitor information from Boeing and the Federal Aviation Administration (FAA) on the impending 737 MAX software enhancements and training requirements," the company said.
"We remain confident that, once certified by the FAA, the enhancements will support the safe operation of the MAX."