British Airways cabin crew will walk out for seven days later this month after talks between the airline and labour unions aimed at averting a strike broke down, dealing a fresh blow to the loss-making carrier, according to Reuters. The Unite union on Friday said BA cabin crew would strike for three days from March. 20 and for four days from March. 27. By law, Unite had until next Monday to announce actions, giving seven days notice of any walkout. "This will probably cost BA something in the region of 20 million pounds ($29.84 million) a day but maybe less since they have some contingency plans in place," said Davy Stockbrokers aviation analyst Stephen Furlong. BA has trained staff from other areas of the company to fill-in as cabin crew during the strike and has said it will hire 23 fully-crewed planes from charter companies to help run flights from Heathrow. The union's 13,000 cabin crew members have twice voted for industrial action as part of a dispute over job losses and changes to working practices, but a 12-day Christmas strike was halted following a successful legal challenge from BA. BA crew have decided not to strike over the Easter holidays, which are spread across the first week of April, because of a public backlash over the planned duration of its December strike. BA shares, which have risen by a quarter so far this year, were 1.4 percent up at 233.8 pence by 1115 GMT.