Ryanair’s profits fell by nearly a third last year to €1bn (£880m) as fuel costs rose and fares fell.
Europe’s biggest discount airline added that profits could be lower this year as fares continue to fall.
For the current financial year, the carrier said it was “cautious” on pricing and had “zero” visibility for the second half of the year.
The figures exclude the loss of €139m from the Austrian airline Lauda it took over last year.
It said that while bookings in the first half of this year were slightly ahead of last year, “fares are lower and we expect this trend will continue through 2019”.
The fuel bill is expected to rise by €460m, but the outlook will also depend on last-minute fares and any impact from Brexit,.
The airline estimates that profits could range between €750m and €950m.
Ryanair is delaying deliveries of five of the Boeing 737 Max planes, which have been grounded because of two fatal crashes, but said it had the “utmost confidence” in the aircraft.
The craft have 4% more seats, are 16% more fuel efficient and noise emissions are 40% lower, but because of the delay to deliveries there will not be any cost benefit for Ryanair until the 2021 financial year.