Holiday company TUI Group said the grounding of its Boeing 737 MAX planes would continue to drag on profits, with a hit of up to €400m possible in its 2020 financial year if the jet does not come back into service by May.
The company, whose main rival Thomas Cook went out of business in September, said its earnings forecasts for the 12 months to the end of September 2020 assumed a €130m hit from the grounding.
But it added that forecast earnings growth of at least 6% depended on the 737 MAX being back in service by the end of April and that an additional €220-270m could be wiped off profits if it was not.
The 737 MAX was grounded globally in March after two crashes attributed to anti-stall software in which a total of 346 people died.
TUI said the groundings had already cost it €293m in the financial year to the end of September 2019 as it paid out to replace the capacity of the 15 MAX planes it operated - 10% of its fleet, with another eight on order.
The boss of Ryanair group this week warned that the model was likely to remain grounded in Europe until April or May, cautioning that it was also possible it would not have any MAX planes for the summer season.
Analysts at Stifel said the MAX uncertainty was overshadowing a time when TUI should be "emerging from a period of capital intensive transition to a brighter future."
TUI's CEO Fritz Joussen said the company would have matched 2018's record earnings had it not been for the 737 MAX grounding.
Instead, full-year earnings before interest, tax and amortisation (EBITA) were down 26% to €893m.
TUI also faced headwinds from overcapacity on routes to Spanish destinations and Brexit uncertainty, factors that were partly behind the failure of Thomas Cook.
TUI, which owns its own cruise ship business, said that it was benefiting from Thomas Cook's demise, with an increase in bookings and higher prices for the current winter and coming summer seasons.
There is still plenty of competition in the European travel market, however, with rivals such as On The Beach and Jet2 also looking to cash in on Thomas Cook's collapse, as well as the relaunch of budget airline EasyJet's holiday business.