More than a million passengers were facing Christmas travel misery tonight as British Airways cabin crew announced a 12-day strike in a bitter row over jobs, pay and working conditions.
Unite stunned the airline by announcing a walkout from December 22 to January 2 following a 9-1 vote in favour of industrial action.
BA said the strikes were "completely unjustified", while rival airlines moved to tempt customers affected by the action.
Len McCluskey, Unite's assistant general secretary, said he hoped the size of the vote would force BA to reopen negotiations.
"More than nine out of 10 staff are saying that what is happening is wrong - they want to be treated with dignity and respect.
"We have taken this decision to disrupt passengers with a heavy heart and we are hoping that the company can still avoid it happening.
"We would like passengers to be angry with the company. It is something of an irony that the people responsible for making BA the best airline in the world are now engaged in a dispute."
Mr McCluskey said the cabin crew were not "mindless militants", but decent men and women who were proud of BA and did not want to bring the company down.
The strike will ground hundreds of flights and cost BA millions of pounds on top of its current losses of around £1.5m (€1.66m) a day.
The union warned of further strikes if the long-running dispute was not resolved.
Cabin crew will receive £30 (€33.4m) a day strike pay, costing Unite more than £500,000 (€556,475) over the 12-day period.
Officials said it was one of the biggest turnouts in a ballot and one of the largest majorities for industrial action.
Hundreds of cabin crew were given the ballot result at a mass meeting at Sandown Park racecourse in Esher, Surrey, and cheered when they heard the news.
Many were in their BA uniform and some had young children in buggies with them.
Mr McCluskey accused BA of pushing workers into a "corner" by imposing the changes, which the airline insisted were vital for its future.
"You don't often get ballot results like this unless there is a deep rooted sense of anxiety, concern and anger."
Unite said it had put forward proposals it believed would have saved almost £60 (€66.7m), including a pay cut.
"The company has consistently refused to accept our proposals and wants more from cabin crew than we believe is necessary.
"We remain willing to discuss any issue with BA, with the help of a third party if necessary.
"We asked the company not to push us into a corner. The imposition has particularly angered our members."
Mr McCluskey made it clear that BA would have to lift the imposition of the changes, including the reduction in cabin crew numbers, before fresh talks could be held.
"The problem with intransigent management is that you can push people so far, but eventually workers will say that enough is enough."
BA said: "British Airways is extremely disappointed that Unite is planning massive disruption for hundreds of thousands of our customers over the Christmas/New Year holiday period.
"A 12-day strike would be completely unjustified and a huge over-reaction to the modest changes we have announced for cabin crew which are intended to help us recover from record financial losses.
"Unite's cynical decision betrays a total lack of concern for our customers, our business and other employees within British Airways."
One male cabin crew member said: "We are conscious of the disruption this will cause and we genuinely don't want to inconvenience the public, but we feel we have no option."
Frances Tuke, a spokeswoman for travel organisation Abta, said: "The strike announcement is bad news for the travel industry.
"People who have booked Christmas and new year package holidays involving BA flights will find that tour operators will either have to re-arrange flights for them or give them a refund."
Bob Atkinson, from travelsupermarket.com said: "This is a double disaster for BA. Its customers are now going to be significantly affected and the airline will take a financial hit from the action."
BA announced earlier that its pension fund deficit had increased by 75% over the past three years to £3.7bn (€4.1bn).
Jim McAuslan, leader of the British Airline Pilots' Association, said: "There can still be a resolution of this conflict even at this, the eleventh hour. The last thing we want to see is the travelling public inconvenienced and BA's long term future damaged,"
Paul Simmons, easyJet's UK general manager, said his airline still had seats available over the Christmas and New Year period.
British Airways chief executive Willie Walsh called the strike "senseless".
"It is very sad that they are seeking to use the Christmas holiday plans and family reunions of hundreds of thousands of people to try to pursue their case," he said.
He added: "We will not be reversing our changes to onboard crew numbers. They have allowed us to accept more than 1,000 requests for voluntary redundancy - and those former colleagues have left the business.
"Unite must understand that there can be no return to the old, inefficient ways if we want to ensure long-term survival in the interests of our customers, shareholders and all our staff."