British Airways cabin crew have voted overwhelmingly in favour of strikes in a dispute over pay, trade union Unite said.
The union said its members backed walkouts by a 4-1 majority, raising the threat of disruption to flights at the British carrier.
At the centre of the dispute are cabin crew who have joined the airline since 2010.
Unite said it involves around 2,500 workers in its so-called "mixed fleet".
It said their jobs were advertised at salaries between stg£21,000 and stg£25,000 - but that in reality they started at just over stg£12,000 plus stg£3 an hour flying pay.
Unite regional officer Matt Smith said: "British Airways' pay rates are indefensible and the crew are at breaking point.
"Mixed Fleet crew earn just over the minimum wage and below the national average.
"Significant numbers of crew are taking on second jobs, many go to work unfit to fly because they can't afford to be sick.
"British Airways bosses need to wake up to the anger and the injustice here."
The union has not indicated when the strikes might happen.
BA said the workers involved represented about 15% of cabin crew and that it had proposed a "fair and reasonable" pay increase.
A spokesman said: "We are extremely disappointed that the union is creating uncertainty for our customers.
"We remain focused on resolving this issue as quickly as possible without any disruption to customers."