American Airlines Group Inc. and United Airlines Holdings Inc. removed Boeing Co.’s grounded 737 Max from their schedules into December, while other carriers are giving up on getting the narrow-body back in time for the Christmas and New Year holidays.

For American, the extension means the cancellation of 140 daily flights through Dec. 3, according to a statement Sunday. While United pulled the Max from its flight plans until Dec. 19, Norwegian Air Shuttle ASA is among the major Max customers that isn’t counting on a return to service until 2020, its interim Chief Executive Officer Geir Karlsen said on Monday.

American, the world’s biggest airline, said it’s confident software updates and a new training regime devised by Boeing will lead to re-certification of the 737 this year.

Southwest Airlines Co., the largest Max operator, has scrubbed the plane from schedules through Jan. 5, while Air Canada is counting it out until Jan. 8 at least. Ryanair Holdings Plc, the biggest European customer, said in July it expects to receive barely half of the 58 jets due for next summer, though the delivery schedule is complicated by its order for a higher-density variant.

The Max, Boeing’s best-selling jet, has been grounded worldwide since March 13 following two crashes within five months that killed 346 people.

The U.S. Federal Aviation Administration is likely to conduct its certification flight for the Max in October, people briefed on the matter said last month. That would broadly match Boeing’s estimate that the aircraft will return to service early in the fourth quarter.

Low Season

Among other major Max buyers, tour operator TUI AG said it sees no operational problems if the plane remains absent this winter, the low season for European vacations, without saying when it expects the model to return.

The company, which has 15 of the aircraft grounded and should have received a further eight, is more concerned about planning for next year and whether it will need to lease in more jets as cover.

Norwegian blamed the grounding of the Max, as well as issues with Rolls-Royce Holdings Plc engines on its Boeing 787 Dreamliners, for a 1.5 billion kroner ($165 million) hit to working capital. It said Monday it needs to push back maturities on some debt.

According to a Dow Jones report, friction between Boeing and regulators worldwide may keep the Max grounded into the Christmas travel season.

Aviation authorities, including those from Europe, Brazil and the U.S., have complained that the planemaker has failed to provide technical details about modifications to the Max’s flight-control computers, Dow Jones said, citing government and pilot union officials.

The complaints stem from a meeting last month in Seattle that was cut short by regulators, Dow Jones said. Boeing will have to resubmit documents on proposed software changes, which must then be vetted by the FAA, the report said. A Boeing spokesman declined to comment on the meeting to Dow Jones.