Multiple airlines are blaming Boeing’s line of 737 Max jets, which were grounded worldwide earlier this year after the second of two deadly crashes within six months, for profit shortfalls that have left some companies struggling to recover.

Reuters reported Friday that American Airlines has cut its profit forecast for the year, warning that the issues thought to have caused a deadly crash in Ethiopia last month are expected to cost the airline as much as $350 million in cancelled flights and other costs.

The airline owns 24 of the 737 Max jets, and grounding those planes forced American Airlines to cancel 1,200 flights heading into the busy summer travel season, according to Reuters. American’s stock shares slipped 3.9 percent in premarket trading Friday on the news.

Norwegian Airlines, which owns 18 of the aircraft, warned Thursday that the company would have difficulty reaching profitability in 2019 due to the jets’ issues.

“Due to the uncertainty related to the Max grounding, the company [sees] increased risk related to the target of a positive net profit in 2019,” the company said according to

The company’s CEO added during an earnings call this week that he doesn’t expect the fleet to be operational in time for summer.

“None of them are of course up and flying, and we don’t expect them to be up and flying this summer,” he said, according to Skift.

Southwest Airlines said in a news release that it would return the planes to operation as soon as possible, while characterizing the grounding of the jets as an expensive start to an otherwise successful year.

“Currently, the timeline is uncertain for the MAX aircraft return to service. In the meantime, we have proactively adjusted our published flight schedules for the next several months and removed all MAX flights through August 5th,” CEO Gary Kelly said in a news release.

“The flight cancellations in first quarter 2019, and the resulting lower available seat mile (ASM, or capacity) growth, year-over-year, created significant pressure on our first quarter unit costs. Flight cancellations are expected to drive unit cost pressure for the duration of the MAX groundings,” he added.