British Airways cabin crew are to strike from May 18-22 inclusive, May 24-28, May 30-June 3 and June 5-9, the Unite union has announced.
Families planning to take half-term holidays and fans travelling to South Africa ahead of the World Cup are among passengers who may be affected by the walkout.
Members of Unite voted not to accept a proposal from the airline which would have ended the year-long row over jobs and staffing allowances.
British Airways accused Unite of “orchestrating” rejection of a “very fair” offer it said addressed all the concerns raised during 14 months of talks.
Cabin crew leaders had been meeting the union’s joint general secretaries to discuss their next move.
Derek Simpson and Tony Woodley said: “BA management should take note of their own employees’ strong rejection of their offer and immediately address the outstanding concerns.”
British Airways said it was “disappointed but not surprised” Unite rejected the offer and said nothing can be gained from more industrial action.
“We urge Unite to put an end to this unnecessary dispute and focus on the best interests of its members. There can be nothing positive to be gained from further strikes,” the airline said.
“Unlike other businesses and airlines, we have avoided compulsory redundancies. Cabin crew face no pay cut or reduction in terms and conditions, and remain the best rewarded in the UK airline industry.”
More than 7,000 union members took part in the latest ballot, with over 5,600 rejecting the deal and 1,375 voting in favour.