Ryanair has tempered its long-term expectations as it is forced to keep running without the Boeing planes it was hoping would be delivered more than six months ago.
The budget carrier said its target to carry 200 million passengers a year would have to wait for a year or two until 2025 or 2026.
It comes as Boeing is battling to ensure its 737 Max planes are able to take to the skies again. The aircraft were grounded after hundreds of people were killed in two crashes.
"It is now likely that our first Max aircraft will not deliver until September or October 2020," Ryanair said in a statement to the Stock Exchange this morning.
It said the late delivery of the "gamechanger" planes, which carry more passengers and burn less fuel, will transform the business over the next decade, but that, "due to these delivery delays, we won't see any of these cost savings until late in the 2021 financial year".
However, there was better news elsewhere as the company cited a strong Christmas and New Year for a 6% rise in customer numbers to 36 million in the three months to the end of December.
It was also able to rake in higher fares during the period, helping to swing the airline from a 66 million euro (£56 million) loss to an 88 million euro (£74 million) profit. Revenue per passenger rose 13%.
Overall revenue jumped 21% to 1.91 billion euros (£1.61 billion) in the three months.
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Fuel costs rose by 14% to 700 million euros (£590 million) because the airline paid more per unit and used more fuel.
It said that annual profit after tax was likely to fall in the middle of the already upgraded 950 million euros to 1.05 billion euros (£800 million to £884 million) target range.
Bookings for the fourth quarter are 1% ahead of the same period last year and are gathering slightly better fares. Full-year passenger growth is expected at 8%, to 154 million.
Shares in Ryanair rose 4% in early trading following the statement.