Two days before Norwegian Air Shuttle ASA discloses its results for 2017, Chief Executive Officer Bjorn Kjos has called the year “a mess” for the carrier after it was hit by plane and pilot shortages at the height of summer.

Norwegian was forced to ground more than 10 Boeing Co. 737 Max jets due to engine snags, delaying operations by six weeks and leaving crews without the flying hours required to cross the Atlantic, Kjos said Tuesday. The debacle cost about 1 billion kroner ($130 million)—including moving staff around and leasing older, less efficient planes.

“2017 was not a good year,” Kjos said in an interview in London. “What could we do? We had already started to sell a lot of tickets. We couldn’t say to the passengers, ‘Sorry we can’t fly you.’ The best thing about 2017 is that it’s now 2018.”

Crews were switched from Norwegian’s premier 787 Dreamliner services to bridge the staffing gap, racking up costs and complexity, according to the CEO. The carrier, which posts 2017 figures Thursday, is estimated to have suffered a loss of 1.43 billion kroner before interest and tax, versus a 1.24 billion-kroner year-earlier profit, according to 13 analyst forecasts collected by Bloomberg.

Kjos said he’s standing by one of the airline industry’s most ambitious expansion plans, pledging to add more flights from London Gatwick airport to South America and Asia, and to use Airbus SE’s new A321neo narrow-body for range-stretching services to Detroit, Minneapolis and Philadelphia.