The union representing British Airways cabin crew failed to win a court injunction to block planned changes to work practices due to start this month.

But Unite said it would press ahead with an industrial action ballot of 14,000 workers that could lead to strikes in the busy Christmas period for BA, which is expected to announce more large financial losses on Friday morning.

Unite went to the High Court to try to stop the flag carrier introducing a series of changes from November 16, including measures to cut by one the number of cabin crew on some long-haul flights.

John Hendy, Unite’s QC, told Mr Justice Butterfield at London’s High Court that BA’s planned changes would “detrimentally affect” staff and passengers on the flights affected by the new procedures.

BA denied this and said that although there would be a slight increase in work for cabin crew, there would be no effect on health and safety and blocking the changes would be commercially disastrous.

The union eventually said its members would “unwillingly” work under the new rotas after the two sides agreed to return to court for a full hearing on February 1.

BA said in a statement later that the changes were “fair and reasonable, given our urgent need to reduce costs so we can move back toward profitability after two years of the worst financial losses in our history”.

The airline will on Friday report its results for the three months to the end of September and some analysts believe it could show pre-tax losses of as much as £145m ($240m).