British Airways cabin crew plan to strike for a total of seven days this month after talks with management over changes to pay and working conditions broke down.

Unite, the union representing around 30,000 cabin crew at the airline, said today that workers will walk out for three days from March 20 and another four days from March 27.

Unite assistant general secretary Len McCluskey added that a new offer made by BA yesterday would be put to a vote by workers and the strike action would be called off if they approved.

However, he said the carrier’s offer fell short of union demands and leaders would not be recommending a favorable vote.

BA said it was “extremely disappointed” at the union’s decision, saying it would cause massive disruption for hundreds of thousands of travellers in the run-up to the Easter holidays.

The airline has been training around 1,000 workers from other departments at the airline to stand in for cabin crew in the event of a walkout.

It said today that it was also working to obtain seats on flights operated by rival airlines to pass on to its own customers.

“Should a strike take place, we will do everything we can to protect our customers’ travel plans as far as possible,” the airline said in a statement.

BA added that it planned to operate all flights from London City airport, including long-haul services to New York. From Gatwick, it plans to operate all long-haul services and about 50 percent of short-haul. From Heathrow, it plans to operate a “substantial part” of both long-haul and short-haul schedules.