Irish low-cost airline Ryanair issued a shock profit warning on Wednesday, sparking a share price plunge.
The airline said the group's annual net profits could miss forecasts owing to intense competition and falling airfares.
The gloomy news sent shockwaves through Europe's airline sector, with shares in Easyjet, British Airways-owner IAG and Germany's Lufthansa also falling heavily.
Ryanair shares were down 14.59 percent at 5.79 euros approaching midday in Dublin trading.
Ryanair "now expects the full-year outturn will be at the lower end of its full-year net profit range of 570-600 million euros ($750-790 million)", it said in a statement.
"However if fares and yields continue to weaken over the coming winter there can be no guarantee that the full-year outturn may not finish at or slightly below the lower end of this range."
Chief executive Michael O'Leary added that the carrier had experienced a dip in fares and yields for the current month and also for October and November.
He blamed this on fierce competition and increased capacity, coupled with a weak sterling/euro exchange rate and poor economic conditions across Europe.
Ryanair "certainly did take the market by surprise", Stephen Furlong, transport analyst with Davy Stockbrokers told AFP.
"We've never had a statement like this at this time of the year from Ryanair."
Ryanair added that it would reduce its winter season capacity, and lowered its full-year traffic target to just under 81 million passengers. That compared with the previous target of 81.5 million.
The Dublin-based airline added that it would roll out lower fares and seat sales mainly in Britain, Scandinavia, Spain and Ireland.
In July, Ryanair had revealed that net profits, or earnings after tax, sank 21 percent to 78.1 million euros in the group's first quarter, or three months to the end of June.
It blamed the impact of higher fuel and operating costs, as well as the timing of Easter and French air traffic control strikes.
Last week, meanwhile, Ryanair was ordered by British regulators to slash its almost 30-percent stake in rival Aer Lingus on grounds of unfair competition.
The Competition Commission (CC) ordered Ryanair to cut its minority holding to just 5.0 percent, confirming a preliminary ruling. Ryanair said it would appeal against the decision, while Aer Lingus welcomed the news.