Southwest Airlines has removed the B737 Max from its schedules up to January 5, 2020, as uncertainty remains over when the Boeing aircraft will be allowed to fly again.

The US carrier had previously cancelled B737 Max flights up to November 2, but said that “With the timing of the Max’s return-to-service still uncertain, we are extending the Max-related flight schedule adjustments”.

Boeing’s Max aircraft are currently grounded worldwide, following two fatal crashes involving the jets.

Southwest said that the move would “proactively remove an average of more than 200 weekday flights from our schedule”.

In a statement the carrier said:

“Southwest Airlines continues to monitor information from Boeing and the Federal Aviation Administration (FAA) on the impending 737 Max software enhancements and training requirements. We remain confident that, once certified by the FAA, the enhancements will support the safe operation of the Max.

“By proactively removing the Max from scheduled service, we can reduce last-minute flight cancellations and unexpected disruptions to our Customers’ travel plans. The limited number of Customers who have already booked their travel and will be affected by our amended schedule will be notified of their re-accommodated travel according to our flexible accommodation procedures.”

Last month American Airlines said that the grounding of its B737 Max fleet would impact its pre-tax profits for this year by approximately $400 million.