The bitter British Airways dispute could cause disruption to flights throughout the summer with cabin crew set to be balloted for fresh industrial action, it was warned today.
Tony Woodley, joint leader of Unite, said a new ballot for strikes could be only a week or so away, as union members staged day two of a five-day walkout.
The union said the series of strikes since last March had now cost BA almost £100 million, with eight further days of action planned.
Mr Woodley also revealed the union had paid out almost £1 million in strike pay, pledging that Unite would not allow the airline to "starve" staff back to work.
He told Unite's annual conference in Manchester the "hard man" stance of BA chief executive Willie Walsh will plunge the airline into a prolonged and "totally needless" summer of disruption.
A fresh ballot will be needed because the 12-week protective legal period for taking industrial action ends in early June.
Mr Woodley said if crew were forced to seek a new mandate for industrial action the blame for this will lie "firmly" with Mr Walsh and his "persistent refusal" to permit a peaceful settlement.
Unite said it believed a deal on cabin crew costs had already been agreed between both parties, adding that the airline could be restored to full operation in time for the peak summer season if the outstanding row over travel concessions was resolved.
Mr Woodley told the 700 delegates that the dispute could be summed up in one word - bullying:
"Bullying that imposes radical changes on our members without agreement, that has seen other BA employees incited against cabin crew with, to their lasting shame, the collusion of scab pilots, that has meant more than 50 of our brothers and sisters suspended or sacked for the crime of sending a text or posting a remark on Facebook, that forbids them from talking about their own dispute in public and that victimises trade unionists by branding them second-class employees for life.
"Well, there is only one thing to do with bullies - that is stand up to them until they learn some manners.
"We all know there is a deal to be struck, one that recognises the real commercial needs and problems of the company as well as our members' legitimate interests.
"But we are not and never will be prepared to see our members and our union humiliated, victimised and reduced to ruins, as Willie Walsh seems to say."
Scores of striking cabin crew later attended a fringe meeting at the conference, speaking out about a "climate of fear" at BA and saying they were too scared to be identified for fear of being disciplined.
"We care about BA - we don't want to see it dragged down to the level of a low-cost airline," said one stewardess.
Mr Woodley told the meeting that Unite's cabin crew branch, Bassa, was ready to recommend acceptance of a deal last Thursday aimed at resolving the dispute, claiming that Mr Walsh was not interested in reaching an agreement.
"They are trying to starve our members back to work - Mr Walsh is trying to give the impression that we will collapse. He has to put aside any idea of achieving regime change in Bassa and start thinking about the well-being of the travelling public."
BA said it had operated more services than planned yesterday, including the reintroduction of all of its services from Heathrow to New York's JFK airport, adding that it would continue to add to its schedule where possible.
"Our global operations went very well throughout the first week of Unite's strike action and got off to another good start today at the beginning of the second series of strikes.
"We have announced a larger schedule at Heathrow for this round of strikes, because of the numbers of crew reporting for work.
"We will continue to operate 100% of our schedule at Gatwick and London City airports. At Heathrow, we will operate more than 70% of long-haul flights (up from more than 60% last week) and more than 55% of short-haul flights (up from more than 50% this week)," the airline said in a statement.
Unite is planning a further five-day strike next week unless the deadlock is broken.
Any further strikes are likely to be in July as it will take Unite four to five weeks to organise a new ballot, raising the prospect of industrial action during the summer school holidays.