Southwest Airlines said it is taking the grounded Boeing 737 Max 8 out of its flight schedule through Sept. 2 given the uncertainty surrounding the plane's return.
American Airlines made a similar move over the weekend, removing the Max from its schedule through Sept. 3.
Southwest had previously taken the plane out of its schedule through Aug. 5, American, Aug. 19. United, which operates 14 Max 9s, has the plane out of its schedule through Aug. 3 and is expected to follow Southwest and American and extend that date soon.
Southwest, the largest U.S. operators of the Max with 34 in its fleet, said the move will affect 100 daily flights. American, the second largest operator with 24 Max 8s, said it had to cancel 115 daily flights.
"By proactively removing the Max from scheduled service, we can reduce last-minute flight cancellations and unexpected disruptions to our customers’ travel plans,'' Southwest said in a statement.
The airline said it will contact all passengers whose reservations will be impacted.
American said its reservations team will contact affected travelers by email or phone. Travelers who bought tickets through a travel agency will be contacted by the agency.
American CEO Doug Parker told the airline's shareholders on Wednesday that the airline's extension beyond Aug. 19 does not mean it thinks the plane won't be certified by the FAA to fly by then. He said the carrier had to make the change due to advance scheduling of flight crews.
"No one should take that as some indication that we don't think the aircraft will be ready by Aug. 19,'' he said.
Parker said "there is an absolute fix for the aircraft.'' Boeing has yet to submit the software fix to the FAA.
The 737 Max has been grounded since March 13 following two fatal crashes in five months.
This article originally appeared on USA TODAY: Flying Southwest or American this summer? Check reservations for new Max 8 cancellations