BERLIN (AP) — European travel operator TUI Group has warned that its profits this year could be a quarter lower than anticipated as a result of the grounding of Boeing 737 Max jets.

TUI, headquartered in Germany, has 15 737 Max aircraft, which have been grounded after two deadly crashes within five months.

Another eight planes were scheduled for delivery by the end of May.

TUI said Friday that if the planes can fly by mid-July underlying earnings will be about 200 million euros ($230 million) lower because of factors including the lease of additional aircraft. An extension until end-September could cost another 100 million euros.

TUI previously forecast "broadly flat" earnings at 1.18 billion euros but they now could be between 17-26 percent lower, depending on when the planes can fly again.