British Airways shareholders will face a union protest today before the airline's annual meeting in London.
The Unite union, currently engaged in a bitter cabin crew dispute with BA, will be handing letters to shareholders as they attend the meeting in Westminster.
The letter urges management to end its "fixation with conflict" over a dispute which already cost BA around £150 million.
It is thought that Unite could be joined in the protest by a delegation from a Spanish union representing workers with the Iberia airline whose merger with BA is expected to be completed in the next few months.
BA cabin crew have staged a series of strikes since March and are currently being balloted on a fresh offer from BA.
The airline said the new offer addresses crews' concerns about future earnings and includes a firm commitment that staff could keep current pay and conditions.
Unite is making no recommendation on whether to accept the proposed deal.
Last year, Unite hired lemmings for a protest outside the annual meeting venue but the animals were taken away after an RSPCA inspector said they showed signs of distress.
In its letter to shareholders, Unite urged them to "use your influence to help bring an end to the strife which is wrecking the airline".
It added that BA had chosen a "destructive" confrontational approach to the dispute which had cost "well over £1 billion if we include industry estimates of future damage to brand and bookings".
This cost had now "vastly outstripped" the savings BA originally sought and it would "take years to recoup this wasted money", the letter said.
Unite added that it was "time for co-operation, not conflict", and that, whatever the result of the ballot over BA's new offer, bad feeling would endure unless significant efforts were made to prevent it.
Unite has said that removal of cabin crew travel concessions remains an obstacle to settling the dispute.
In the letter today, Unite said: "If management want to restore morale and team spirit at BA then, whatever the result of our ballot on the offer, it needs to do one thing above all: restore travel concessions in full to all cabin crew. It won't cost a penny. And it would be a gesture worth millions."
The Spanish CCOO union, which represents Iberia workers, issued a statement today saying it was "extremely concerned with the way senior BA management has instigated a conflict-based approach to industrial relations in the current dispute with cabin crew".
The statement went on: "Although CCOO believes that the merger with BA is to the benefit of our members, we have grave reservations over the style of management, particularly in respect of labour issues.
"Should a similar approach be instituted within the new joint company, or imported into Iberia, then we are clear that it will be vigorously opposed."
Addressing shareholders at the meeting, BA chairman Martin Broughton said the airline's chief executive Willie Walsh had often been depicted by Unite and Unite's cabin crew branch BASSA as "adopting a confrontational approach to industrial relations".
Mr Broughton said that "on the contrary", Mr Walsh and his team had successfully negotiated new modernised working practices with 16 separate union bargaining groups across the business.
Saying that BASSA had "distorted management's proposals" and spread alarm at what Mr Walsh might do, Mr Broughton went on: "Management must have the right to manage. BASSA has failed its members. They have misrepresented management to their members. They have misrepresented their members' views to management.
"They have declined to negotiate and thus frequently failed to represent their members' views at all. They have made promises to their members they cannot deliver. The (BA) board's patience with BASSA has now been exhausted."
Mr Broughton said: "While it is very regrettable that we have found ourselves in a fight with highly-valued and professional members of staff (and I include those who have been on strike but continue to act professionally on their return to work), we will win the right to manage."
Mr Walsh told shareholders said "some issues remain to be concluded" in the dispute but that he was "pleased that Unite is currently balloting its members on our proposals".
He went on: "We believe this offer provides a genuine opportunity to end this dispute."
Mr Walsh said that the airline had been able to operate many flights during earlier strikes, adding that if there was further industrial action, BA aimed to fly 100% of its long-haul operations."