Beleaguered BA has posted record annual losses of £531 million.
The airline - facing more strikes on Monday in a bitter dispute with trade union Unite - has been hit by recession, a harsh winter and a first wave of industrial action in March.
The slide into the red is slightly less than the £600 million feared, but brings BA's total losses for the past two years to £932 million after a £401 million reverse the previous year.
British Airways said revenues plunged by £1 billion, although this was offset by falling fuel costs as well as savings elsewhere in the business.
Chief executive Willie Walsh also fired a broadside at unions after Unite won its appeal against their latest strikes being ruled out on a technicality.
"Returning the business to profitability requires permanent change across the company and it's disappointing that our cabin crew union fails to recognise that," he warned.
He added that the current financial year "could hardly have had a worse start" due to the disruption caused by Iceland's volcanic eruption, which closed most of European airspace for almost a week in April.
Following Thursday's court decision, 15 days of strikes are due to kick off on Monday.
But the group said market conditions were showing improvement and BA is expecting to break even this year following its heavy losses.