Thousands of British Airways cabin crew are to hold a fresh ballot on strikes, raising a renewed threat of disruption to flights.
Unite said 13,000 of its members at the airline would vote again on whether to take industrial action in a long-running dispute over jobs, pay and working conditions.
The cabin crew were due to stage 12 days of strikes over Christmas, but BA took legal action to prevent the action going ahead.
The High Court ruled that the strikes would have been unlawful because Unite had balloted workers who had subsequently left the airline.
The previous ballot returned a 9-1 majority in favour of action in an 80% turnout, which the union said reflected the anger of cabin crew at imposed changes to their working conditions.
The latest move follows a failure to reach an agreement despite talks over the past few weeks.
Unite said there was still no deal on the crucial issues of imposed changes to the workload and working conditions of the airline's cabin crew.
Len McCluskey, assistant general secretary of Unite, said: "We have been engaged in intensive discussions with the company over the last few days, but unfortunately we have not been able to secure an agreement yet.
"We therefore have to honour our commitment to give our members the voice they were denied by the courts before Christmas, and hold a fresh ballot for industrial action."
The ballot will start in a week's time and raises the prospect of action in the run-up to the busy Easter period.