Ryanair is planning capacity cuts, more "aggressive" seat sales, and lower prices after issuing a shock profit warning.
In a statement to the stock exchange, the airline said full-year profits would be "at the lower end" of previous guidance of €570m to €600m.
Boss Michael O’Leary blamed the summer heatwave, the high cost of holidays in the eurozone, increased capacity and competition in the UK and Ireland and the weaker pound.
He warned that if the current trends continue, profits might even slip below the forecasted range, which would be the first time in 10 years that Ryanair has missed its profit target.
Faced with a weaker-than-expected outlook for September, October and November, Ryanair said it would "selectively reduce" its winter season capacity, cutting its annual traffic target from more than 81.5m to just under 81m passengers.
O’Leary added: "We are also rolling out a range of lower fares and aggressive seat sales particularly in those markets mainly UK, Scandinavia, Spain and Ireland."
Shares in Ryanair dropped 15% in early trading before recovering to 11% lower at the end of the day.
The news also had a knock-on effect on the share price of other airlines and travel companies.
Rival easyJet saw its shares fall 65p to 1215p while British Airways parent company IAG lost 3.7p to 291p.
Meanwhile, Tui was down 11.1p to 334.6p and Thomas Cook down 6.9p to 135.7p.
