Thomas Cook cabin crew have voted by 3-1 in favour of a strike in a row over health and safety, said the Unite union.
They have voted to strike over changes being made to their rest breaks.
Cabin crew will be allowed one 20-minute break over 12 hours, according to Unite, Britain’s largest union.
The strike could take place during the school summer holidays, but a date has not yet been confirmed.
A spokesman for Thomas Cook Airlines said: "We're disappointed Unite cabin crew members have taken the decision to vote for strike action.
"The safety of both our people and our customers is our top priority and we rigorously adhere to the rules around crew breaks.
"We're committed to working with Unite to address their concerns and have already met with the conciliation service Acas to try to find a solution.
"Meanwhile, we've put together plans to ensure that our customers will still be able to go on holiday, despite any possible strike action."