British Airways on Monday warned that it expected to make a loss of about 150 million pounds in the company's 2008-2009 financial year.
In a trading update, BA blamed the deteriorating economic outlook, rising non-fuel costs and the falling value of the British pound.
"Further economic weakness in January and the outlook for February and March combined with the fall in sterling are impacting our outlook for the year," BA said in a statement to the London Stock Exchange.
"Costs are being equally impacted by foreign exchange, and non-fuel costs are now expected to rise by 8.0 per cent year on year compared to our previous guidance of 5.0 per cent."
The carrier added: "At current exchange rates, the year to 31 March 2009 is now expected to be an operating loss of some 150 million pounds."
In reaction, BA shares sank 5.40 per cent to 138.30 pence in late afternoon trade on London's FTSE 100 index of leading shares, which was up 3.88 per cent at 4,209.89 points.
The airline added today that it would record an operating loss of about 50 million pounds in its third quarter which runs to the end of December 2008.